"I once loved a boy, a bonnie bonnie boy" is in Broadwood and Fuller Maitland's 'English County Songs, and JFSS 1, 274, 1904; JFSS 2, 82, 1905. It's the one descended, indirectly, from "Cupid's Trappan". A version of that, and most, or all, of the songs mentioned by John Moulden above will be found in DT. That doesn't necessarily mean they will fit the tunes as given by Vaughn Williams.