Pmd stands for "Post mint damage" most likely someone sanded that quarter down, maybe they wanted to see the copper core?
could we see the edge that is smooth with no copper please THIS THREAD IS USELESS WITHOUT PICURES OF THE EDGE
The outside layers of the coin is 25% nickel and 75% copper which have a nickel color, whereas the center is 100% copper. In your photo of the side, at the edge farthest to left side of photo, I can see the 3 layers. If the layer closest to the part worn down doesn't show both of the outer layers, it is because someone reduced the edge by sanding or grinding it down with a very fine abrasive, so it is PMD whether intentional or not by previous owner. Jim