Karl Kissner, the executor of his aunt's estate when she passed away found 37 rare baseball cards in mint condition underneath an old doll house in the attic.
The cards fetched a combined $566,000 at an auction at the National Sports Collectors Convention in Baltimore.
Kissner says he knew his aunt was a packrat, so he made sure he went through everything carefully.
"You had to open every envelope, open every book," Kissner said.
"So knowing that, we went through [her things] very meticulously. Had we gone through in a rampage, we may not have spotted those cards and they would have went in the hopper."
Kissner believes the cards belonged to his grandfather, who was the owner of a meat market and probably used them as promotional handouts many years ago.
This find is considered one of the biggest and most exciting finds in the history of baseball card collecting.
The money made from the cards will now be evenly divided among 20 cousins.