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.