Mojo bags come from the African practice of mojuba bags. The African slaves brought these practice to American with them. They evolved into the mojo bag or what is also called gris-gris bag. A mojo bag is like a spell that you carry with you. It is filled with herbs, crystals, and other magical ingredients. These bags can be created for 
Love
Money
Protection
Good Fortune/Luck
Healing
Attraction
Power
Domination
Fertility