|Bronze coin of Gordian III from Hadrianopolis showing Demeter in her chariot.|
Hades was a powerful god, one of three brothers who shared the whole world between them - the others being Zeus, who ruled the land surface, and Poseidon, god of the sea.
|Bronze drachm of Trajan|
showing Triptolemos distributing wheat.
Don't be distracted by the way the coin seems to say "PIANO". That's part of the name of its town of origin, in Greek lettering: AΔPIANOΠOΛEITΩN, meaning "from Hadrianopolis."
Demeter later lent the same carriage to her foster son Triptolemos, and some coins show him on his mission to distribute wheat and the knowledge of agriculture throughout the world. Here's one, this time from Alexandria. He is holding up a fold of his cloak so that it can hold the grain, and flinging it out with his right hand.
In some vase paintings, the chariot itself is winged, and is drawn by more ordinary snakes.
The Roman equivalent of Demeter was the goddess Ceres, from whose name we get the word "cereal."