For all intents and purposes. Numismatically, it is a damaged cent.... Somebody ground down the reverse and counter-punched it as some type of place holder. Bingo card? Poker game? Only the person that created the piece could answer that for you.... Welcome to the world of coin collecting!
DEFDAM - Definitely Damaged Not a mint error of any kind. Just an altered Cent. When the counterstamp was applied on the Reverse it flattened Lincoln's face on the Obverse because of the pressure. Thanks for sharing though.
When I lived in England my Golf partner used to do that with old half pennies and his initials. Used them as ball markers
I know an older woman who used to be an avid golfer for most of her life. She had to give it up at about age 75 though because of hip issues. She had me donate a lot of her golf equipment and in one of the bags I found a penny that was sort of like that, grounded off on one side. I brought it to her thinking it was something maybe important like a cherished good luck charm and she explained it was just something she used as a ball marker.