There are two versions (with MIDI files) in our Digital Tradition Folk song Database (links above). There is a Digital Tradition mirror called Yet Another Digital Tradition that offers our tunes in a variety of formats, including "sheet music." The first version is from John Jacob Niles, and the second is from Cecil Sharp. As Malcolm says, the Niles version is a "reworking," but I think it's the better-known version. I suppose what I sing is a simplified rendition of the Niles version. I don't like his ornamentation, and I don't sing falsetto.
I don't see the song in The Ballad Book of John Jacob Niles. Is the Niles version published in a songbook somewhere?

In another thread, Malcolm pointed out two examples (with sheet music) in the Max Hunter Collection:

Black, Black, Was the Color of My True Love's Hair

Black Is the Color of My True Love's Hair

-Joe Offer- (e-mail sent)