Interesting stuff. But what I haven't come across are references to is material relating directly to the slave and post slave period, or to accounts collected from the field. It always seems to be people much later retelling the story.
There's a book which doesn't seem to have been mentioned on these threads which is really worth having for anyone interested in these things, Harold Courlander's Negro Folk Music, published originally in 1963, though there's a modern paperback edition with Amazon.
He makes the point that sometimes the interpretation of other songs which emphasise their possible coded meaning may be a misinterpretation, and that their direct religious meaning was more significant at the time.
"A large number of spirituals and anthems were so worded that they could have a disguised meaning; but it is not safe to assume...that they were created as anything else but religious songs."
Of "Follow the Drinking Gourd" he writes "There undoubtedly were some songs which served the slaves in their efforts to escape. For example Follow the Drinking Gourd is thought to have been a kind of oral map leading out of slave territory. The Drinking Gourd presumably was the Big Dipper, by which one readily locates the North Star:
When the sun comes back and the first quail calls
Follow the drinking gourd,
For the old man is waiting to carry you to freedom
If you follow the drinking gourd.
The river bank will make a very good road
The dead trees show you the way.
Left foot, peg foot, travelling on
Follow the drinking gourd.
"These and other stanzas are found in Silber (Irwin Silber, Songs of the Civil War, published 1960). Making due allowance for rearrangements that may have been made in the lyrics since the song was first sung, a careful reading nevertheless gives the impression that the song is not couched in traditional Negro images or vernacular and that the entire effect is literary and contrived. The legend attributed to it says in fact that it was taught to the slaves by a peg-leg ex-sailor who wandered round the countryside telling them how to escape to the North.
But once again, retelling, with a reference only dating to 1969 for those verses. It would be interesting to see what the version from 1867.