Well, the '64 Half Dollar turned out to be uninteresting. How about this dime? A mint error or damage after the fact? It's hard to tell from the pics but both sides are concave with the edge curling in.
Thanks everyone! This was part of an accumulation of coins I inherited. The dime was in its own separate container, while all the other were in rolls. Maybe it was my grandfather who tried the spoon on it. I'm sure it was he who drilled holes in some of the others!