The American Memory collection of the Library of Congress is especially rich in primary documents about the African American experience. They have 17 different collections, including sheet music, slave narratives, broadsides, Frederick Douglass papers, personal narratives from the South, baseball and Jackie Robinson.
One of the most useful is this collection of African American pamphlets from 1824 to 1909.
The WMU Libraries owns many instructional videos and DVDs, including streaming videos, that you can use in your research. You can search for these in Library Search on the Libraries' home page. This video could provide you with useful primary documentation about the slavery experience in America.