On the spectrum of baseball rarities, a signature from Shoeless Joe Jackson — the turn-of-the-century star who never learned to read or write — is high on the list.

Jackson never spent a day in school, instead joining his father doing odd jobs at the Brandon Mill in his hometown of Greenville, S.C., as a child and taking the baseball path to stardom from the time he was barely a teenager.

Jackson, who hit .408 for Cleveland in 1911 and was banned by baseball for his role — a highly disputed role — in the 1919 Black Sox Scandal, did sign a few important documents along the way, though. One of those rare signatures is up for auction right now, with the bidding at Leland’s ending on Friday. It’s a signed mortgage voucher from 1916. At the time of this story’s publishing, the high bid is $20,886.

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