Gwern-y-Cleppa

Iolo Morganwg (aka Edward Williams) “found” an old manuscript that said there was an eisteddfod here in the time of King Edward the third. But actually Mr Williams was a very imaginative man and spent a lot of time “discovering” old druidic Welsh manuscripts and poems, so it is probably a complete and utter fib.
books.google.co.uk/books?id=6jREAAAAIAAJ&pg=RA1-PA491