It's the quintessential Irish Samhain food: colcannon.
The name means “white-head cabbage”: col (as in “cole slaw”) + ceann (as in Kennedy, “black head”) + finn (“white”), but cabbage is only one of the autumnal triumverate that make up this classic of the peasant kitchen, onions and (of course) potatoes being the others. Before the coming of the spud, likely turnips—that other classic Samhain root vegetable—would have been the third.
How many foods do you know that have (and deserve) their own song? You can hear Mary Black singing its praises here. We sing this song every Samhain. Then we dig in.
Colcannon is good, hearty winter food, but the Samhain batch is special because then you put in the divinatory tokens before you serve it: the coin (for money), the ring (for love), the thimble (some say, spinsterhood; others, creativity).
One Samhain my covensib Kay got the coin. “I could certainly use the money,” she said, “but it doesn't seem very likely; I'm already at the top of my pay grade.”