"A proper new ballad entitled The Wind hath blown my Plaid away, or, A Discourse betwixt a young [Wolman and the Elphin Knight,' a broadside in black letter in the Pepysian library, bound up at the end of a copy of Blind Harry's 'Wallace,' Edin. 1673."
Quote from introduction to The Elfin Knight, Child, "The English and Scottish Popular Ballads."
See "Pills to Purge...," post by Jim Carroll, above.

Child comments on ballads similar to the Elfin Knight in German and other European languages.

Gammer Gurton's Garland, 1810 (quoted as G in Child)-
1.
Can you make me a cambrick shirt,
Parsley, sage, rosemary and thyme
Without any seam or needle work?
Ans you shall be a true lover of mine.
........

Versions beginning with a line on Scarborough Fair, 1891, 1893 (Child, Appendix to The Elfin Knight)
1.
Is any of you going to Scarborough Fair?
Remember me to a lad as lives there;
Remember me to a lad as lives there;
For once he was a true lover of mine.
2
Tell him to bring me an acre of land ....

Much of the above in the linked thread; perhaps some of this useful as fill.