Craig-y-Ddinas in the Brecon Beacons is the location of some wonderful Faerie Tales - one of which I have come across with two alternate endings. I'll tell you them both and you can decide for yourself which one you like best.
Many years ago a young boy called Gitto Bach (little Griffith) would tend his fathers sheep on Craig-y-Ddinas. When he came home at the end of the day he'd often bring small pieces of bright white paper with letters on, about the size of a coin, which he said the faeries had given to him.
One day he went out to play as usual but people started to worry when he didn't come home. All the people of the village tried to find him but with no success, though some children did find pieces of paper like those that Gitto Bach had shown them. Eventually they gave up looking.
Then two years later Gitto's mother heard a knock at her door. When she opened the door she saw her son looking just as he had the day he disappeared. Under his arm he held a parcel. When she asked where he'd been all that time, Gitto was surprised as he thought he had only been gone for a day (because faery time is different to our own). Then Gitto showed his mother the gift he had brought from the faeries. They opened the parcel to see the most beautiful clothes made out of the same white paper without a stitch in sight. His mother recognised these to be faerie clothes and threw them on the fire.
The other version tells us that Gitto Bach was given faerie money but sworn to secrecy. The money turned to paper after he told others where it was from.
But the story doesn't end there as the man who told this tale was interested in faeries himself and enlisted the help of a local gypsy in order to see them. She asked him to get a four leaved clover and nine grains of wheat which he should place on a book that she had given him, and one moonlit night they went up to the top of Craig-y-Ddinas. There the gypsy rubbed an ointment on the man's eyes and immediately he could see the faeries dressed all in white and dancing to the music of tiny harps. A moment later they curled up with their knees bent into their chests and rolled down the rock and vanished into the distance.
Craig-y-Ddinas (meaning Rock of the Fortress) is found where the County boundaries of Neath Port Talbot, Powys and Rhondda Cynon Taff meet and at the confluence of the Rivers Mellte and Sychryd.