" but most don't mention any folklore connected to druids, so I'm assuming they are elder antiquarians fanciful names."

Yup, but nevertheless interesting in how prehistoric stones figured in thinking..most 'druidon' naming would have probably come from the 18th century when the idea got floated around. History says of the 'celtic' period that it was the sacred tree/bile* that was to be found as the centre of their villages. Later, early 'desert' monks would have followed the old roman roads, which in turn went by the barrows and circles of an earlier age - thats why, sometimes, churches are on old sites or nearby. Conversion from one faith to another ie paganism to christianity was probably conducted by some poor creature of a monk standing atop a barrow declaiming the wicked ways of the old gods ..

* and of course there was an interesting discussion about a fossilised tree/stone in Bryn Celli ddu's chamber. (see Rupert Soskin's photo) http://www.themodernantiquarian.com/site/352/bryn_celli_ddu.html