One of the links on the Llangynfelyn website mentions another local site – two stones in a field belonging to the Yurglawdd farm (there is an Erglodd farm in the vicinity? which would sound similar). Allegedly, once a third stone appears then that’ll be the end of the world. I wonder if the two stones are still there?
llangynfelyn.org/dogfennau/bedd_taliesin_mynegiad.html
(This super website has masses of information on the stones).
3.11
I can’t see them mentioned on Coflein. The folklore book above says they are ‘in a field called Llettyngharad on this farm [Eurglawdd], which is in the parish of Llanfihangel Genau’r Glyn, there are two stones respecting which an ancient prophecy says that when the third appears, the end of the world will be at hand’. Erglodd was the site of a mine.