Todays tale is one of the Three Welsh Romances that are included in The Mabinogion. They bear certain resemblances to the Arthurian legends found in the work of Chrétien de Troyes a French poet who wrote some of the most famous Medieval literature. It's not know who wrote the stories first... were these romances a retelling of his work in the Welsh language or did de Troyes use a more ancient Celtic legend as the basis for his tales. Either way, this story may seem familiar because it's not dissimilar to the tale of Perceval and the story of the Grail.
In my modern retelling in The Mab, this is the story of Peredur, the Monster and the Serpent of the Cairn. The legendary King Arthur appears for the first time in our stories. Arthur probably did exist, he was likely to be a Romano-British warlord who fought against Saxon invaders in the 5th century, our first written reference to him are Welsh, but he wasn't necessarily Welsh, as he pops up in battles all over modern day Britain.
The Battle of Camlan was supposedly Arthurs final fight, where he was defeated by Mordred. Camlan still exists as a place in three different parts of Wales. One of them is just down the road from me, take a look around the suggested sites of the battle on this rather charming website.
If you want to read the original tale then you can read a copy of the Lady Charlotte Guest text here. Sadly I can't even begin to find a decent online reading of this story... it seems to be one of the less popular tales.
The fibre today is inspired by the serpent that Peredur kill in one of his many adventures. There's not a lot spare of this vibrant green, but both Green Woodpecker, and Ivy are very very similar in colour, and you can find them all in the shop.