Not strictly a hymnal, but there is a 1992 Dover reprint of Harold Courlander's "Negro Folk Music, U.S.A." (original 1963) that does include a number of "anthems, spirituals," etc.

I picked up a new copy fairly recently for $7.95, so it's apparently still readily available, and cheap enough to be interesting as a "fill-out" addition to a person's ref library.

ISBN 0-486-27350-4, about 300 pages, approx 40 tunes scored, with some additional text-only lyrics.

John