The depiction of Ceres on this antoninianus of Salonina from Antioch strikes me as odd because the goddess appears to be wearing a polos, which isn't one of her usual attributes. Rather, she is typically depicted as veiled or wearing a crown made of grain. Cornelia Salonina, AD 253-268. Roman silvered billon antoninianus, 3.15 g, 22.7 mm, 5 h. Antioch, AD 265 Obv: SALONINA AVG, diademed and draped bust right on crescent. Rev: CERERI AVG, Ceres, veiled and wearing polos, seated left, holding grain head with right hand and long torch in left. Branch in exergue. Refs: RIC 90; Göbl 1637e, Cohen 22; RCV 10627. Cohen describes the headdress as a modius: Compare, for example, these other Roman coins in my collection depicting Ceres, none of which portray her wearing a polos: It's not entirely unheard of, however, and this small 1st-2nd century AD figurine portrays the goddess with a polos and holding a torch (bent) and grain ears. But I'm unaware of Roman coins depicting her in this way. While I'd love to see any examples you have of Demeter or Ceres wearing a polos, please feel free to post anything you feel is relevant.
These provincial coins of Faustina II from Pautalia in Thrace depict Demeter, the Greek equivalent of Ceres. She doesn't wear a polos on these coins, either:
M. VOLTEIUS M.F. ROMAN REPUBLIC; GENS VOLTEIA AR Denarius OBVERSE: Head of Bacchus or Liber right, wreathed with ivy REVERSE: Ceres holding two torches, in biga of serpents right. Symbol in left field (double headed axe) Rome 76BC 3.75g, 18mm Volteia 3; Cr385/3; Sear 314 L FURIUS CN F BROCCHUS ROMAN REPUBLIC; GENS FURIA AR Denarius OBVERSE: Bust of Ceres right between wheat-ear and barley-corn; III VIR across field, BROCCHI below REVERSE: Curule chair between fasces; L. FVRI/CN. F above Rome 63 BC 3.9g, 20mm Cr414/1; Furia 23 VESPASIANAR Denarius OBVERSE: IMP CAESAR VESPASIANVS AVG, laureate head right REVERSE: TR POT X COS VIIII, Ceres seated left, holding grain ears and torch Struck at Rome, 79AD 3.4g, 18mm RIC 1062 FAUSTINA Sr AE As OBVERSE: DIVA FAVSTINA, draped bust right REVERSE: AVGVSTA S-C, Ceres standing left holding torch & corn-ears Struck at Rome, 148-161AD 13.5g, 27mm RIC 1171
I regret that I only have one Ceres, and she is pretty worn: RI Titus 79-81 CE AR Denarius Ceres seated corn ear poppy torch I always felt that Ceres was similar to Tanit and Demeter: Carthage mint 2nd Punic War 203-201 BCE BI 1½ Shekels 24mm 9.4g Grain Wreathed Head of Tanit - Horse standing R head L, raised foreleg Pellet SNG COP 394
