Not at all unusual on the east coast. The WWII ships coming back from the Mediterranean had dredged sand for ballast, and dumped it here. From there the sand could have wound up everywhere and whose dad who served in North Africa didn't bring home some ancient souvenir. Mine did. I found two Roman coins in NJ and saw a friend dig one outside of Charleston, SC some time ago. A kid found quite a few on the eastern shore of MD a few years ago.