Gwyddno Long Shank
The father of Elphin.
He possessed a magical basket – a fish-weir which yielded many salmon and a mwys or basket which could feed 100 persons at a time. In origin, Gwyddno Garanhir may have been a god whose purpose appears to be either agricultural, as the mwys signifies, or with a more watery association, as reflected in the fish-weir. His basket or hamper was said to have been one of the Thirteen Treasures of Britain.
As one of his forty tasks, the warrior Culhwch had to obtain the basket from Gwyddno, so that the giant Ysbaddaden could eat from it during his daughter’s wedding feast.
Under the name of Dewrarth Wledig, Gwyddno Garanhir was said to have been, during the fifth century, the King of the lost realm of Cantre’r Gwaelod or the Lowland Hundred, which is said to lie under the waters of Cardigan Bay.
See also
Mwys Gwyddno | The Legend of King Arthur
Source
Culhwch and Olwen | Late 11th century