Sharon Bowen thought her late husband was a bit crazy for buying a scrapbook filled with black and white photos of Cleveland ballplayers from the early 1900s — but not anymore. It turns out that book held what may be the only autographed photo of Shoeless Joe Jackson, the Holy Grail of baseball signatures.

Jackson, who was tossed out of baseball for throwing the 1919 World Series and remembered in the movie “Field of Dreams,” was illiterate and rarely signed anything but paychecks and legal documents, making his autographs among the rarest in sports.

How many Jackson signatures are in existence isn’t clear, but most experts agree that it’s probably less than 100. But this is the first signed photo authenticated by autograph experts, according to Heritage Auctions, which is handling the sale of the century-old photograph this month.

It could fetch at least $100,000, according to the Dallas-based auction house.