Welcome to the neighborhood @Hamhocksleep77 ! It looks like a re-punched mintmark (RPM)……."S over S". ~ Chris
you may want to check this .. looks like 001 http://www.varietyvista.com/02b LC RPMs Vol 2/RPMs 1970S.htm but can't see the rest of the coin (front and back) to know for sure. if you check the details for the 001 you can check for everything else http://www.varietyvista.com/02b LC RPMs Vol 2/1970SRPM001.htm