Case Description: King Pryderi of Dyfed accuses Gwydion of theft. Gwydion swapped Pryderi's prized pigs—given to him by the king of the Underworld—in a deal. He only gave the king of Dyfed horses and dogs, along with some jewelry, but the animals turned into mushrooms the next day.
Case Status: Dismissed. When Math and Pryderi went to war over the pigs, Gwydion bumped off the rival ruler.