"John Riley", also known as "Johnny Riley", "The Broken Token" and "A Fair Young Maid All in Her Garden", among other titles is a traditional English folk song (Roud #264). It is not found in the Child collection. The song is derived from Homer's Odyssey, filtered through the 17th century English folk ballad tradition.
The song's theme, that of the "disguised true lover", is a theme in a number of traditional folk ballads, generically known as "The Broken Token" family. Other songs from this family in this collection are:
      "Claudy Banks"
      "Dark Eyed Sailor".
"John Riley" was recorded by Joan Baez, Judy Collins, Peggy Seeger, The Byrds and others.
It was printed in Cecil Sharp's English Folk Songs from the Southern Appalachians (1932), Alan Lomax's The Folk Songs of North America (1960), Pete Seeger's The Bells of Rhymney (1964) and Peggy Seeger's Folk Songs of Peggy Seeger (1964).
I learned it from the Joan Baez recording.