Welcome to Coin Talk, You may find this site interesting.http://www.coinflation.com/coins/1964-Silver-Kennedy-Half-Dollar-Value.html
The mere existence of a mintmark on the OBVERSE of a 1964-D half would be an earthshattering numismatic story. Color me dubious.
Is this the way you have to treat new people who make a mistake. New to coins and just realized error.
Sorry for my error, it is on reverse. I think I posted a picture of both. I will be getting out of your hair.
Ah. Reverse. Nice coin. The obverse photo is a wee bit "shaky", but this is a well-preserved example.
Very nice coin, looks to be well struck, I would put it in a hard plastic holder. The toning around the edge is proof that its been in storage for a while.
Welcome to CT... If i am not mistaken i believe that only the 1964d was mint marked on the reverse. I would consider changing the storage method and go with either a hard airtite or a 2x2 flip just to prevent adverse damage from plastics breaking down over time. Happy hunting.