It was on the end of a coin roll and when the end of the roll was crimped there was a lot of friction on the coin which wore that circle into the coin.
I have a bunch of UNC mint rolls and 25% of them have a coin on the end of the roll like that.
I agree with Coinman. I used to call those shotgun crimps. Those were caused when the machine crimping the coin used too much force to close the paper coin roll and damaged the coin. Post mint damage :-(