Click here to get to the thread with full information on Art's CD. The lyrics are in the database - search under sheepfold or be lazy and click here.
I've found this song on a few CD's, and each seems to be connected somehow to the infamous Art Thieme. I see in the database that Art may have learned it from Jerry Epstein. Sure enough, it's on Jerry's great CD called Time Has Made a Change in Me. Here's what Jerry says in the notes:

The Massa of the Sheepfold is from a genre of pseudo-Black dialect "spirituals" that had a vogue around the turn of the century. I learned it my first summer at Pinewoods Camp (1965) from Susan Richardson Slyman. She told me that she had learned it from Bill Boyun who had collected it in Maine. Lucy simpson has found a printed version in an old hymnal where it was titled "De Massa Ob De Sheepfold." Not a prime example of political correctness in this day and age. Good song, though. I get more requests for this than for any other song.

CD's from Art and Jerry are available at Folk-Legacy Records.

Art's CD booklet goes on to say that Cindy Mangsen and Anne Hills learned it from Art and recorded it on their Never Grow Up CD, and Cindy told Art she found the poem in an "outrageous Afro-American dialect" written by Sarah Pratt McLean Greene (born in Connecticut in 1856, died in Massachusetts in 1935).
All three recordings of the song are great, but I like Art's best.
-Joe Offer-

Also see this thread.