Error Experts- What's going on with this Massachusetts state quarter?
I bought this on the cheap as a filled die error at a show yesterday. I liked that only of the center of the coin had any detail and the reverse was HAMMERED, maybe indicating the obverse was struck through something instead. When I got it home and under good lighting and magnification, I noticed a groove running around the inside rim of the obverse and I'm not sure how it got there, other than something outside the mint. What do you think?