I believe "mojo" comes out of Africa, not America. the following from the encyclopedia
Terminology and manner of use:
The word Mojo traces its origins to Africa and entered the English language during the era of slavery in the USA. It has been widely known from the 19th century and early 20th century to the present. Other regional names for mojo bags, or for specific types of mojos, include gree-gree (a Bantu word typically spelled gris-gris by people in Louisiana because of the state's Francophone origins), mojo hand, conjure bag, conjure hand, toby, jomo, and nation sack. In Haiti, the usual name for this sort of charm bag among those of African descent is a wanga, oanga, or wanger.