Emperor Gordian III (238-244 AD), silver antoninianus (double-denarius), obverse inscription IMP GORDIANVS PIVS FEL AVG. Reverse: FELICIT TEMPOR, Felicitas (Happiness) standing holding long caduceus and cornucopia. Sear catalogue (millennium edition) #8607, CV $20 in VF. Swamperbob's probably right on the money for your specimen.
Coins of this emperor are very common, and often found in a high state of preservation - almost as if the entire coinage went straight from the mint into holes in the ground. The silver fineness at the time was quite low - somewhere around 30%.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis