One day, I'm at my mother-in-law's house and she asks me if I would take something to her storage shed. Being the great guy that I am, I say, "Sure thing!" WhenI get to the shed, she unlocks it and, lo and behold, there is a huge black cauldron right there in the doorway. Before I thought, I said, "So THAT'S where you keep it!"
You know, I've always had my suspicions...
Anyway, the cauldron story is a lead in on the next Treasure of Britain. The Cauldron of Dyrnwch the Giant (Pair Dyrnwch Gawr) is a large cauldron that only works for the brave. If you are a coward, you can heat the water up all you want, but the meat will never boil. However, if you were a brave man, it would boil almost immediately.
There is an Irish story that is similar and the two are most certainly connected. In this story the owner is Diwrnach, who is sometimes described as a giant. Just as the British treasure, the cauldron is picky about who cooks it. Along comes this guy, Olwen, who has a quest to gather several treasures together, including this cauldron (much the same as the idea of gathering the 13 treasures together). Arthur, ever the helpful friend to Olwen, had his man persuade Diwrnach to give it up willingly, but Diwrnach's steward refuses to let it go. After trying again, Arthur just takes the thing, fills it with treasure he took from Ireland, and goes home.
Also, the Preiddeu Annwfn, a poem that may have been written by Taliesin, the cauldron is not only mentioned, but described as well. The poem goes on to detail a trip by Arthur into Annwfn (I believe to be a section of the Otherworld). While there, he finds the cauldron and here we learn that it is not some big black witches cauldron (such as you might find in my mother-in-law's storage shed), but it is finished in pearl.
R. S. Loomis suggests that this cauldron was an early Celtic idea that the holy grail evolved from. Bernard Cornwell, in his series about Arthur, has the cauldron also with the ability to restore life (drawing from this connection Loomis makes). As I have already stated, I think this is an excellent book series and provides a nice alternative view of Arthur.
Whatever the case, this cauldron seems to me to be a strange treasure. Maybe a cauldron that turns things to gold or a cauldron that feeds thousands or something. Refusing to boil food for a coward... well, it just doesn't seem, I don't know, all that treasurey* to me.
*I am an English teacher, so if I say "treasurey" is a word, then it is!