Artie Gore made his major-league debut as an umpire in 1947 and his fellow umpires autographed a ball used in that game for him.
That game on April 15, 1947 also was Jackie Robinson's first in the majors.
Now it's being auctioned off for more than $20,000 at the FanFest in New York as part of festivities for Tuesday night's All-Star game.
Gore's nephew, Richard Flaherty, found the ball last year among the belongings at his father's home in Watertown, Mass. Flaherty says his father was Gore's brother-in-law and died soon after the discovery. Gore died in 1986.
Gore also had a Ted Williams jersey from the mid-40s that is being auctioned off. Online bidding for that has passed $70,000.
Live bidding begins on Tuesday.