Have you tried familysearch.com
they are missionaries who documented everyone they came into contact with.
It is free and ran by the church of laterday saints.
Clayton is also known as Layton...there are many Claytons on Native American Rolls who are Cherokee and Chickasaw mixes.
I am a Layton and have done exstensive research on the Native Americans in my family .
I found a direct ancestor on this website: http://www.cherokeediscovery.com
And have found many Laytons on the 1st Mounted Rifles Cherokee union and confederates of the civil war. It is a HUGE place to fine ancestors whom are Native American.