I first read The Crow Goddess decades ago, when I was an undergraduate. I must have found it in a second-hand bookshop somewhere – I have no recollection of where – because I’m pretty sure that it was long out of print even then. Still, if you can find a copy, it’s very much worth snapping it up as it’s the best work I’ve read of life in the ancient world of the Celts.
The Plant Dôn: the Children of Dôn, are introduced in the Fourth Branch of the Mabinogi. Who is Dôn, though? I have heard prominent people in contemporary Druidry describe Dôn as an earth goddess; I believe that they are mistaken, and that she is something quite different.