A treasure trove collection of rare works by Keith Haring will soon be going on display and auction, courtesy of his lifelong best friend, Kermit Oswald. Before the Subway drawings, the Club 57 scene and the celebrity collaborations, Keith Haring dreamed of New York from his hometown of Kutztown, Pennsylvania. Often by his side was Oswald, a friend since kindergarten.

The pair first met at church, aged five, passing notes during services in Kutztown. As boys, they bonded over a shared love of “creating things” and began drawing together. By their teenage years, they were regularly taking the three-hour bus journey to New York City, spending afternoons exploring museums and galleries that would shape Haring’s artistic ambitions.

Their friendship endured after Haring moved to New York in 1978 to study at the School of Visual Arts. The two exchanged letters, gifts and visits throughout Haring’s meteoric rise in the 1980s. Oswald helped install Haring’s exhibitions, while Haring became godfather to Oswald’s child.

Now, decades after Keith Haring’s death, a rare collection of works from Oswald’s personal archive is being unveiled and going on auction. Titled Haring House: Works From the Collection of Kermit Oswald, the exhibition offers a strikingly intimate portrait of one of the most celebrated artists of the 20th century. Many of the pieces have never been publicly displayed before.

The centrepiece of the sale is a 1985 self-portrait depicting Haring’s bespectacled, expressionless head attached to the body of a sphinx. It is one of only six self-portraits on canvas that Haring is known to have made and carries an estimated value of $3 million to $5 million. Oswald has described it as one of the most beautiful paintings Haring ever created.

Among the exhibition’s most unexpected works is a bright yellow baby crib and matching dresser painted by Haring in 1986 after the birth of Oswald’s first child. Unable to afford new furniture, Oswald and his wife reused the crib Oswald himself had slept in as a baby.

He explained to The Guardian, “I got it, and I painted it yellow, then Keith came over, we had a few beers, and he painted the rest of it.”

Haring added squiggles, dots, dachshunds inspired by the family dog, and caricatures of Oswald and his wife, Lisa. Both pieces are estimated at $250,000 to $350,000. The works are on public exhibition at the Breuer in New York as of May 2 and will go up for auction on May 14 and 15.

Haring, famed for his activism, nightlife imagery and celebration of queer culture in 1980s New York, died from AIDS-related complications on February 16, 1990, at the age of 31. Before his death, he asked Oswald to tell his parents he was HIV-positive, a request his friend honoured.

Reflecting on the loss of Haring and so many of his generation, Oswald told The Guardian: “I think New York would be different if he had lived, if all of them had lived. When I think about all those artists and dancers and musicians, if they had stayed, New York would be such a different place.”