That would be considered a counterstamp done after it left the Mint. An alteration made by adding the letter D. Not a Mint Error of any kind.
Oh ok thank you I wish I knew more of the coin talk language but I understand that it’s not a error coin
Well thank you everyone this is a nice page I will ask and post more when I come across more coins like this
These are metalic rods with letters and numbers at the end. Place it on a coin and hit it with a hammer. It will create an incused punch on the coin such as yours. Fairly simple..
It would be best to start your own separate unique thread. Pictures of both sides of the coins. Welcome to CoinTalk!