If you visit Gravlaba you will see a cairn and some standing stones. But don't look too hard just in case. One day some visitors to this site were just too nosy and they saw some Picts (fairies) dancing in the knowe to celebrate the birth of a child. These two people didn't just intrude and stare, they tried to nick off with a keg of buttermilk that had been laid in for the party! It's not surprising, but the Picts turned them to stone for their rudeness. The keg of buttermilk got turned to stone too (bit of a mix up with the curses I think). So there used to be three stones there, but now apparently there are only two. Perhaps the Picts eventually worked out how to get their buttermilk back.
(very likely in Grinsell's 'Folklore of Prehstoric Sites in Britain')