My husband got this dime about 2 weeks ago. It looks like its never been circulated and the back has a weird double line "crease." We would love to know anyone's speculation and if its worth anything.
Welcome to CT!! Looks like a bead of solder to me. The "groove" in the middle probably held something like a safety pin to be able to put it on your shirt. I believe some people did this for the March of Dimes charities. I have one, though not so well soldered, with the safety pin still attached.