The University of North Carolina electronic texts are amazing in their volume and diversity. The large collection listed here covers first-person narratives of slaves and whites of the Civil War period. It would take days to read them all.
And this is just a small part of the material being put on the internet in the "docsouth" (Documenting the American South) websites.
First Person Narratives

The Bradford volume on Tubman (link by Masato, above) has a couple of spiritual songs not listed in the Cleveland Index nor in the Spirituals Permathread.