Mentioned in related threads, I'm sure, but there's always:
(Ghost) Riders in the Sky
If You Could Read My Mind (ghost from a wishing well in it)
Witchy Woman
The Great Silkie of Sule Skerry
Long Black Veil (the narrator is already dead)
Miss Bailey's Ghost
Love Potion No. 9 (gypsy has magic potions)
The Dry Bones
Black Magic Woman
Hotel California
Three Ravens / Twa Corbies
The Farmer's Curst Wife (so bad the Devil kicks her out of hell and back to her husband)
Zombie Jamboree


Not all "folk," but they tend to fit the theme.

and, of course, no end to murder ballads and the like