I agree with GUEST 18 Mar 07 - 08:29 AM wrote.

I believe that 'jelly' in Leadbelly's song is a shortened form of the African American slang term 'jelly roll'. See this information from http://nfo.net/usa/etymol.html "THE ROOTS OF "JAZZ"" A little bit of Etymology.

"'jelly roll'
--Black slang from the nineteenth century for the vulva, with various related meanings, i.e. sexual intercourse, a loving woman, a man obsessed with finding same. "'What yo' want?' she asked softly. 'Jelly roll?'" (Thomas Wolfe, 'Look Homeward Angel,' 1929). The term probably derives from 'jelly,' meaning semen: "Give her cold jelly to take up her belly, And once a day swinge her again" (John Fletcher, 'The Beggar's Bush,' 1622). Related expressions include 'jelly bag,' referring both to the scrotum and the female genitals; 'jerk [one's] jelly,' to masturbate; and 'jelly,' a good-looking woman. 'Jelly Roll' appears in many blues songs, such as "I Ain't Gonna Give Nobody None o' My Jelly Roll," "Nobody in Town Can Bake a Jelly Roll Like Mine," and "Jelly Roll Blues," the last by Ferdinand Joseph La Menthe "Jelly Roll" Morton (1885-1941)."