He won her at the court of her father, Hefeydd the Old, by her aid. She bore Pwyll a son, who vanished. Her women killed a puppy and smeared its blood on her, to avoid blame at the child's loss. As punishment, Rhiannon spent seven years telling her story to all comers and bearing them, like a horse, to the court.
The child, meanwhile, turned up at the court of Teyrnon, whose mares foaled on May eve and lost the foals mysteriously. When Teirnon kept watch, he saved a foal from a mysterious beast and also discovered, outside the stable, a child, whom he and his wife adopted. Then child grew to young manhood in seven years, and was given the foal rescued on the night he was found. Teirnon recognised the child as the son of Pwyll and returned him to his family, where he was named Pryderi ("worry") by his mother.
Later, after Pwyll's death, Rhiannon married Manawydan, brother of Bran and Branwen and son of Llyr, a great magician. One day, all of Dyfed turned into a wasteland, and only Rhiannon, Manawydan, Pryderi, and his wife Cigfa, were spared. Manawydan and Pryderi out hunting followed an enormous white boar into a caer, where Pryderi saw a golden bowl; when he touched it, he was enspelled. Rhiannon went after him and fell under the same spell the caer then vanished, taking them with it. She was rescued when Manawydan captured the wife of their enemy, Llwyd, who was taking revenge for the illtreatment of Gwawl.