The Garbo collection, the first sale to be announced for the fall art season by Sotheby's, was made public yesterday at the same time that Christie's in New York was releasing its first announcement of art to be auctioned in the fall: van Gogh's ''Vase With Daisies and Poppies'' from 1890. The van Gogh still life has hung at the Albright-Knox Art Gallery in Buffalo since 1962. It is estimated that it will bring $12 million to $16 million, with the proceeds from its sale to go to two Buffalo museums and a foundation.

John L. Marion, Sotheby's chairman in North America, said yesterday that in the 1950's and 60's Garbo frequented the salesrooms of Sotheby's predecessor, Parke-Bernet Galleries, on Madison Avenue at 76th Street. He would greet her and offer her a catalogue, he said.

''I remember her coming to the exhibitions with some frequency and going around and looking at everything,'' Mr. Marion recalled. ''To the best of my recollection she never bid in person at an auction. But Buford Chisholm, a decorator, used to bid for her at the auctions.'' Mr. Marion said he believed this was how Garbo acquired the large Savonnerie rug that was in her living room.

David J. Nash, who heads fine-art sales at Sotheby's, said he was not disappointed in what he found on his first visit to the apartment on East 52d Street, at the East River, where Garbo had lived since 1953. The large living room where most of the art was hung, he said, appeared to have been ''decorated around the paintings.'' A panel had been installed above the fireplace to hang one of her three Renoirs, ''Gabrielle and Coco Reading,'' from 1906. The presale estimate is $8 million to $10 million. ''Curiously, she bought the three Renoirs in the same month of 1942,'' Mr. Nash said.

Advice From Alfred Barr

The earliest Renoir, a study of the artist's nephew Edmond, which is estimated to bring $5 million to $6 million, was bought from the gallery of Jacques Seligman on 57th Street in Manhattan.

''Miss Garbo went into the gallery and asked about the painting,'' Mr. Nash said, recalling that Alfred H. Barr Jr., then head of the Museum of Modern Art, had appeared at Garbo's side and said, '''Young lady, you won't go far wrong with that painting.'''

Sotheby's is to auction two postwar abstract paintings from the Garbo collection in London in December. Both works have the same title, ''Composition,'' and are by Jean-Michel Atlan and Serge Poliakoff.

The vibrant van Gogh painting of daisies and poppies at Christie's was completed in June 1890, several weeks before the artist committed suicide. It was acquired in the 1920's by A. Conger Goodyear, who made his fortune in the family lumber business and was the first president of the Museum of Modern Art in New York, serving from 1929 to 1939.

How the Painting Was Bought

A son, George Forman Goodyear, recalled his father's purchase in a telephone interview yesterday from his home in Buffalo, saying: ''He bought the van Gogh for $12,000 in the 1920's at Wildenstein in New York. He had always been an art collector. He gave me two of his paintings: the van Gogh and a Gauguin which I sold in 1959.''

The younger Mr. Goodyear, a lawyer and businessman, made a partial gift of the van Gogh to the Albright-Knox Art Gallery in Buffalo in 1962. In 1982, the museum owned 60 percent of the painting. ''I thought the gift I had made to the art gallery by 1982, valued for my income tax at about $1 million, was disproportionate to my benefactions,'' he said.

Mr. Goodyear, who is 84, said he spoke to his friend Seymour Knox, the museum's benefactor, who is 92, and discussed the idea of making fractional gifts to three recipients: the Albright-Knox (65 percent), the Buffalo Museum of Science, where Mr. Goodyear is president emeritus (28 percent), and the University at Buffalo Foundation (7 percent) to benefit the State University at Buffalo.

The Albright-Knox issued a statement yesterday saying that while it regrets the loss of the van Gogh still life, it owns another, more valuable van Gogh. The painting, ''Old Mill,'' was a bequest from A. Conger Goodyear, who died in 1964. When asked yesterday how he would feel if the van Gogh was sold to a foreign buyer, George Goodyear said: ''I would not be unhappy if it went to Japan. The world has got to get together and this is one way for this to happen.''