I *did* post the original, and it's the 17th century song yes. As found in "Ancient Ballads and Songs" (Edinburough, 1875 - can be found at archive.org). It's just called "The Gowans So Gay" there but I guess I transposed the title. In fact I'd say that it's a tune with at least some tradition wouldn't you? :-p
Anyway, Theriot most certainly did not compose the original. Perhaps she composed the music. I wouldn't know as I can't find anything but recordings of the OTHER versions which would have to be different because they're written differently and even tell different stories. This is why I came to you guys.
It's because of this I've taken to researching songs when I find I like them, as I'm learning that a lot of people claim they "composed" something when in fact it's a folk song. I was at a thing 2 weekends ago and was told The House of the Rising Sun was copyright. No. No it's not. Especially not my version.
The folk police are going to have to take me in kicking and screaming. I'm not letting go of my Appalachian instrument. Mwahahahaaaaa.