Valley So Low: Southern Mountain Stories by Manly Wade Wellman

A collection of uncanny tales. Some are Silver John. Some feature other men who wander about and know some of the matters -- each one with his tales grouped -- and it's clear that it's one continuity, with their loosely knowing each other, with Judge Pursuivant the sage old man of their knowledge. Others are people who get mixed up in such matters and may or may not escape.

One can see how he was listed in the Appendix N as a D&D source.