Nikko just posted a nice example from London and I recently got one from Trier.
Constantine I
Summer A.D. 307
26x29mm 7.7gm
FL VAL CONSTANTINVS NOB CAES; Laureate and cuirassed bust right.
MARTI PATRI PROPVGNATORI; Mars, naked but for chlamys, advancing right, holding transverse spear, shield on left arm. S/A in fields.
In ex. PTR
RIC VI Trier 730