@Wheels these are quite common wheat cents worth a small amount over face at most. Here is a link to a site about wheat cents for more information. http://www.lincolncentresource.com/index.html
I have this 1956 d with what it seems to be an s to the left of it, maybe I am tricking myself. I need better pictures.
@Wheels if you find a reference that looks like or close to yours. Just remember that the MM position has to be the same.