Brewer's Dictionary of Phrase and Fable
I came across this gem of a reference book today while reading Terry Pratchett's Katharine Briggs Memorial Lecture, "Imaginary Worlds, Real Stories" (Folklore 111 (2000): 159-168).
Update: I should have mentioned that Pratchett identifies Brewer's Dictionary of Phrase and Fable, Robert Graves' The White Goddess, and Dermot Mac Manus's The Middle Kingdom as influential childhood reading. He writes
There was no pattern to this. I just chose the books that looked interesting. I tended towards folklore rather than mythology, because gods seemed rather dull and stupid and in any case mythology just seemed to be the folklore of the winners.
What was going on, I now realise, was the stealthy laying down of the coal measures I was subsequently to mine as a professional author. I can't remember where I first heard of the Dunmow Flitch, or the King of the Bean, or the Horseman's Word, or the Hunting of the Wren ... in a sense, I've never not known them."
folklore | terry pratchett