Here's another song that mentions a black cat bone:
Copied from http://www.luckymojo.com/bluesjimtampabogan.html

JIM TAMPA BLUES
(Lucille Bogan)

Hey, Jim Tampa, hey, Jim Tampa,
Hey, Jim Tampa, you treat your woman so mean.
You treat your tommies like a woman you ain't never seen.

Womens all know my man, call him Mister Tampa Long.
(spoken) Why shouldn't they call me? They know my name.
Womens all know my man, call him Mister Tampa Long.
He made so much money, women, when the weather was warm.
(spoken) Ah no, I ain't made no money in my life.

My man's got five womens. I can call 'em by their natural names.
He's got five womens, call them by their natural names.
(spoken) Lord, I don't know how they do it.
And all them repeaters sound just the same.
(spoken) I ain't just the same, though, no, no.

It must be a black cat bone. Jomo can't work that hard.
(spoken) Oh, what is a jomo anyhow? Tell me.
It must be a black cat bone. Jomo can't work that hard.
(spoken) What kind of a thing is it?
Every time I wake up, Jim Tampa's in my yard.

I can stand right here, five miles down the road
I can stand right here, five miles down the road,
Yeah, to get in the way Jim Tampa used to go.
---
SINGER: Lucille Bogan, spoken comments by Papa Charlie Jackson
DATE OF REC.: c. June 1927
ORIGINAL ISSUE: Paramount 12504
REISSUE: Yazoo L-1017 ...

[Tommies: variant of donies or doneys (whores). Jomo: variant of mojo (charm)]