I am curious if this is considered a RPM (mint mark)? Also, there is a chip on the top of the eye in Liberty which I don't know if this was caused during minting or just post mint damage - The coin is circulated but in really good shape.
PMD and possibly a RPM, Have you checked it yet? There are 113 of them. http://varietyvista.com/02b LC RPMs Vol 2/RPMs 1960D (1-60).htm
The RPM is East, so using the Search at Coppercoins can save you time. Your photos aren’t clear enough to attribute against, but in hand you should have an easier time. Look for location first and then try to match markers. It may be this one - https://coppercoins.com/lincoln/diestate.php?date=1960&die_id=1960d1mm024&die_state=mds