The 1860 census of the free people of South Carolina shows the Newton famil-- please notice that it includes people with the last name of Newton, living together, who are both white and black. (Column 6)
Notice that Robert and Polly have no children younger than 17; Mildred 30 - half of Polly's age - and her children are 10, 7 and 2 and explicitly carry the "Newton" name.
To one of my students: these are your ancestors.
You should investigate this.