At the southwestern end of Mynydd Rhiw there is a very prominent conical outcrop called Clip y Gylfinhir:
Mrs Williams, of Pwll Defaid, told me that the rock opposite, called Clip y Gylfinhir, on Bodwydog Mountain, a part of Mynydd y Rhiw, was the resort of the Tylwyth Teg, and that they revelled there when it was covered in mist; she added that a neighbouring farm called Bodermud Isa’, was well known at one time as the place the fairies came to do their baking.
From Celtic Folkore – John Rhys (1901)
The name translates at Crag of the Curlew (literally “long beak”).