I have the original sheet music for several late 19th century versions and they're all composites with different authors who have simply presented their versions. However the earliest actually state that the 'Died for love' verses came from a Cornish version of that lament and indeed they are close to one of the thousands of versions, one found in the trad song book 'Canow Kernow' of Cornish songs.

The various interesting posts here that take a serious historical note give the origins of just about all of the text in the well-known version as it was sung in the 20th century.

Both American students and the Minstrel diaspora took some popular and traditional material to make some of their repertoire. A good example is 'My Bonny' basically a student song, but closely derived from Harry Clifton's 'Send back my Barney' of the 1860s which was popular in America in the late 19th century. As these songs were rewritten/ put together and given a new tune in America I have no doubts they should be considered American. (with some British input).