That is just a stain on the on the coin that looks like a 'D'. That location is not where the mint mark would be for a Denver cent. (since 1990, the mint marks are part of the design on the coin)

Also the mint mark would be raised. This is a Philly cent that didn't have a mint mark for them until 2017.

Also the mint mark would be raised. This is a Philly cent that didn't have a mint mark for them until 2017.



















