The term BEAN SOURCE can be broken down into three crossword solutions: SOYA (4 letters), COCA (4 letters), and HEAD (4 letters). SOYA refers to the soybean, a legume native to East Asia that is widely cultivated for its edible bean. COCA is a reference to the COCA plant, which is native to South America and is the source of cocaine. Finally, HEAD is a reference to the common bean, which is a variety of the species Phaseolus vulgaris and is native to Central and South America.