Sorry but not an error. Post Mint Damage. Worth 5 cents. Someone hit it with a die punch most likely. Welcome to Cointalk!
Hi Nat, Sorry , no error, unless you call what the igmo who hit this coin with a hammer and a numeral O stencil did to it, an error. That's referred to as PMD or Post Mint Damage, something that is done to the coin after it left the mint. A lot of people think finds like these are cute ( I do ) and keep them in a sort of " oddities " box for Show and Tell with friends. Thanks for posting. Keep 'em comin' . !!