G'day,
Professor Francis James Child of Harvard Uni published "The English and Scottish Popular Ballads" in five volumes between 1882 and 1898. They contain words to 305 ballads, with many variants of each, and with extensive notes on the origins of each.

In those days a ballad meant "a folk song that tells a story". For example Child #2 is "The Elfin Knight", a very old ballad of which "Scarborough Fair" is a more recent version.

Volume V has about 50 tunes; "The Singing Tradition of Child's Popular Ballads" by Bertrand Harris Bronson has hundreds of tunes for these ballads including many variants unknown to Child. There is an abridged version of this.

Child was not a collector, he relied on others in America and the UK to provide him with the songs. This is an incredible piece of work.

Cheers,
Alan (who is now late for a meeting)