Tracing my husbands cherokee roots?

I have been searching for his grandmothers family lineage everywhere and all i can find is recent info. his dad tells us she was cherokee and the pics we have of her look very much so. Her maiden name was vergie c or n cobb (different sources) born in Georgia in 1940. died in 1997 as vergie n willis. 2 sons and a daughter. her dads name was h.p. cobb sr. and stepmom was katie cobb. im trying to find a family tree or some kind of info on her birth parents and grandparents because he wants to know if he really is of native decent. please help me out... i'm stuck?