People spend their lives dreaming of buried treasure right in their own backyards. That dream just came true for Karl Kissner, a restaurant owner in the small midwestern town of Defiance, Ohio.

Cleaning out his late grandfather's attic, Kissner opened a dirty cardboard box to find it filled with old baseball cards in near-mint condition.

The cards pictured beautiful colored drawings of some of the greatest players in the sport's history, includingTy Cobb, Honus Wagner and Cy Young.

Not sure what he had found, Kissner sent them to a sports memorabilia authenticator who says they are genuine, from an extremely rare series of cards issued in 1910. The company calls it the most significant find in baseball card history, and says the cards could be worth millions when they are auctioned.

Kissner compared his discovery to finding the Mona Lisa in his attic.