A family from Michigan was recently cleaning out an old farmhouse after a death in the family and they came across some vintage football and boxing trading cards.

They almost threw them out, but decided not to, and did a little bit of research.

From a story from Grand Rapids tv station WXMI, they took the collection to Legends Sports & Games in Michigan, their local collectibles store that has vintage cards and made a very nice discovery about one of the cards. The owner of the store said that they had “the Holy Grail of football cards.”

It was a card that was issued in 1894 by the Mayo Tobacco Works Of Richmond, Virginia. It was of Harvard’s John Dunlop – part of the rarest football set ever distributed, plus the only set from the 19th century solely dedicated to football.

Dunlop’s name was left off of the card, so it’s considered “anonymous.” Lou Brown is the president of Legends Sports & Games in Michigan, estimates the card being worth $10,000 dollars. Can you imagine finding something like this in your own home?