The Peter Paul & Mary version may be copyrighted, but all they did was glue together two traditional (public domain) songs, and add a few words from another one. Click here for a recent discussion of the subject.

The two versions MMario mentions should do you nicely. I think that the music has been transcribed from the Watersons' recording, and whoever did it has accidentally incorporated the harmony part into the tune; (easily done) if you can separate them out, you should have a ready-made arrangement. If you would like, send me a message and I'll send you an image of the staff notation for the basic melody so you can fit them together.

Malcolm