Dug 2 holes in my back yard. One had a pin or something. Looks like copper. 1923 on the front. In the other hole was a bunch of nails and a 1970 'stinkin Lincoln' penny. I got hot and went inside. OhioDeb
The 1923 pin might be an add-on to an assoaciation pin. They would be issued annually denoting some service for that year. Just a guess. I can't think of a reason to denote the particular year on it's own.