I have several quarters and Kennedy half dollars with these circular grooves cut into them. Any ideas on where this damage came from?
Welcome to CT. Your coins, as mentioned already, are damage from a coin crimping machine. I run across them occasionally, but it looks like you hit the jack pot with so many. LOL NAV, no added value. Not only NAV, but if the coin was a keeper, it would be damaged and reduce the value. Keep looking.