That was an unexpected find. Uncirculated set tokens are included in uncirculated coin sets produced at the U.S. Mint specifically for coin collectors. They are minted on a penny planchet, though technically carry no legal tender status and have no face value. Finding one in circulation is uncommon to say the least, and finding this one in AU+ condition is probably even less common.

The 1924 came from the same box, as did about 10 other 40’s and 50’s wheat cents, 2 Canadians, and a decent selection of AU type 60’s-80’s pennies.