What was going on when I was born?

MUSHROOM mania is the current epidemic sweeping through American produce markets. Indeed, the abundance in specialty-food shops of what were once called toadstools - chanterelles, boletes, oyster mushrooms, morels, cauliflower mushrooms, shiitakes, meadow mushrooms and many other varieties - makes it hard to believe that there was a time when even commonplace fat, white, fresh cultivated mushrooms were unknown in our supermarkets. ''Americans went from not knowing anything to going wild about the stuff,'' said Giorgio DeLuca of Dean & DeLuca in SoHo. ''I don't know why - maybe it's part of the health thing.'' His food shop at 121 Prince Street (Greene Street) has, for a number of years, stocked fresh wild mushrooms, imported and domestic.

The United States said today that the Soviet Union had begun deploying a new intercontinental nuclear missile in violation of the 1979 treaty limiting offensive strategic weapons. Secretary of Defense Caspar W. Weinberger said in a speech that he could ''confirm officially'' that deployment of the single-warhead missile, known as the SS-25, had begun. The State Department spokesman, Bernard Kalb, said the Soviet Government had informed the United States that SS-25's had been deployed. [In Sofia, Bulgaria, according to CBS News, a Soviet spokesman, Vladimir B. Lomeiko, denied that the deployment was a treaty violation. Mr. Lomeiko, in Sofia for a Warsaw Pact meeting, affirmed the Soviet position that the SS-25 was a modification of an existing weapon, the SS-13, and that the modification was permitted by treaty.] Reagan Looks to Gorbachev Talks Meanwhile, President Reagan, on the eve of his visit to the United Nations, said that he was ''determined to build a more constructive relationship'' with the Soviet Union and to seek reductions in the nuclear arsenals of the two countries. [Page A3.] Mr. Weinberger's remarks on the SS-25 missile seemed intended to portray the Soviet Union as a violator of international agreements when there is debate about a new United States interpretation of the 1972 treaty limiting antiballistic missile defenses.

Colleges in the New York area, faced with mounting student and parental concern over AIDS, have started programs to teach students and staff members about the disease. Some college officials began the programs after students or teachers contracted the disease, but most say they are acting because they are sure there will be cases. The colleges report they are also working to set policies on such issues as whether AIDS victims will be allowed to remain in dormitories and whether other students in the dorm will be told of the victim's illness, problems that are now handled on a case-by-case basis. The officials said educational programs could slow the spread of the disease, acquired immune deficiency syndrome. They also said the programs might allay what they see as irrational fears of AIDS that have led on some campuses to incidents of harassment of homosexuals, the group most likely to contract the usually fatal disease.

Serenity usually returns when the couture houses take over the runways during the week of ready-to-wear openings. In these collections, couture designers are more concerned with making wearable clothes than with carving new design paths. Their presentations are consequently more soothing. This season is no exception. Valentino, who shows his couture collection in Rome but chooses to introduce his ready-to-wear here, and Hubert de Givenchy both showed calm, attractive collections for spring and summer.

Schools Chancellor Nathan Quinones said yesterday that he would seek the immediate dismissal of nearly half the community school board members in New York City for failing to file financial-disclosure statements, as required by state law. At a news conference at Board of Education headquarters in downtown Brooklyn with James F. Regan, president of the board, Mr. Quinones said the city would ask the State Education Commissioner today to dismiss 126 of the board members. The action would affect 28 of the 32 boards, each of which has nine members elected for three-year terms. 'Example of Lawlessness' ''This drastic action is necessary,'' the Board of Education said in a resolution passed last night, ''because to permit public officers to violate the law with impunity will set an example of lawlessness for schoolchildren under their care, will undermine the public's confidence in such officers and will impede the board's and the Chancellor's efforts to insure that corruption and conflicts of interest do not interfere with the proper functioning of the New York City school system.''

Treasury Secretary James A. Baker 3d said today that the Government was not ''arm-twisting'' commercial banks or promising either Federal guarantees or regulatory relief in its campaign to persuade the banks to lend an extra $20 billion to developing countries over three years. ''If the banks participate in this it will be because they find it is in their self-interest,'' he insisted at a hearing before the House Banking Committee. ''They've got loans in trouble. It's like any other workout situation. It's possible that reflows will make bad loans into good loans.''

Can the American computer industry design the software for ''Star Wars''? During the last year, this central issue in the research surrounding President Reagan's Strategic Defense Initiative has emerged as the premier problem facing the nation's top software designers. Already it has fractured computer experts, both in industry and academe, into two bitterly divided camps. On Monday night, the controversy over the proposal's feasibility came to the nation's mecca of computer research, the Massachusetts Institute of Technology, where a two-hour debate pitted a pair of scientific advisers to the Pentagon against two scientists who called the project a waste of the software industry's most precious resource - its programming talent. The debate was the first public airing of a technical and political dispute that has dominated the pages of industry journals and served as grist for lunchtime arguments in corporate cafeterias from Boston's Route 128 to California's Silicon Valley.

SHE met him two years ago at a fraternity party on a neighboring campus. His dashing good looks, she recalls now, coupled with his shy grin and friendly manner made him appear ''sweet, but not macho.'' They talked and danced for hours, and later that evening, he took her in his arms and they kissed. When he asked if she would like to get something to eat, she agreed. But instead of heading toward a nearby restaurant, he swerved onto a side street, pulled over to the curb and stopped the car. Then he raped her. The attack - upon a 20-year-old junior at Carlow College in Pittsburgh - and others like it constitute a growing problem on college campuses, according to educators and counselors at rape crisis centers.

The state's top judge called yesterday for a drive to improve New York's deteriorated court buildings, saying that they presented a picture of ''esthetic revulsion'' rather than dignity. The Chief Judge of the State, Sol Wachtler, said local officials, who are responsible for maintaining the courts in their communities, had in many instances failed to do their job. If things do not improve, he warned, he will invoke state law empowering court adminstrators to withhold local assistance funds from counties, cities and villages and to do the job themselves. In a speech last night at the City Bar Association, Judge Wachtler called for a ''comprehensive and audacious program'' to prevent further deterioration and to build new court buildings.

Many corporate executives who have always considered themselves a breed apart from commercial bankers are probably wishing they were in the bankers' shoes these days. As one big bank after another has reported its earnings for the third quarter, it has become clear that, as a group, they are currently among the most prosperous businesses in the nation. In contrast to generally lackluster earnings throughout most of corporate America, most of the largest commercial banks managed to sport earnings gains that were well into the double digits. They did so despite the sluggish rate of economic growth that plagued all companies and despite, in their own cases, the continued specter of troubled Latin American debt.

Senator Paul Laxalt said today that President Ferdinand E. Marcos had agreed to permit American observers at Philippine elections in 1986 and 1987, and to relax his control over the Philippine military. Mr. Laxalt, who reported to President Reagan today on his informal diplomatic mission last week, said in a statement that the promises were ''positive steps'' toward the political and military initiatives urged by the Administration. ''We now have a base line from which future reforms can be assessed,'' said Mr. Laxalt, a Nevada Republican. 'No Hostile Messages' Mr. Laxalt said that contrary to what some Administration officials had earlier told reporters, ''there were no hostile messages delivered on my part, and there was no rejection of our views on President Marcos's part.''

International The United States welcomed as ''statesmanlike, thoughtful and forward-looking'' the peace proposals outlined Monday by Israeli Prime Minister Shimon Peres at the United Nations. [Page A1, Column 6.] Washington deplored the bombing by Israeli planes of the Palestine Liberation Organization headquarters outside Tunis on Oct. 1 that killed 60 Palestinians and 12 Tunisians. Deputy Secretary of State John C. Whitehead, who was sent to help damaged relations with Tunisia, also said that Washington ''deplored all acts of terrorism.'' [A15:1.]