One of the songs sung by Helen Schneyer (available from Folk Legacy) mentioned by Ferrara above is Joan Boyd's "Fountain Filled With Blood," which takes off from an Appalachian Baptist hymn and turns the religious imagery into powerful protests:
"There is a river filled with blood
That once ran so beautiful and grand
'Til the strip miners tore down our mountainsides
Now it runs brown with the blood of our land."
That verse sent shivers up my spine when I first heard it.