Gaddy Clan

I was born in Lumberton North Carolina, My mothers name was Julia Gaddy, she had 4 sisters, Lillian, Hester, Ruth and Doretha and 4 brothers. Her mother's name Julia Thompson, before she married my grandfather James Gaddy. My grandfather was an indian and my grandmother was black. I'm trying to get any information regarding my grandfather's indian heritage. I believe he was related to the Lumbee indians in Lumberton NC. Any information would be helpful.