Constantine I, AE follis, Lyons mint. 

FL VAL CONSTANTINVS NOB C, laureate, draped and cuirassed bust right, seen from the back.
MARTI PATRI CONSERVATORI, Mars, naked but for helmet, standing right, holding spear and resting left hand on shield. 

N in left field. 
Mintmark PLG.

RIC VI, Lyons 241 var (obv legend).

Contributed by Richard Demarco of Carpe Diem Numismatics, Oct. 2024.