Who is Burris Ewell from To Kill a Mockingbird?

In Harper Lee's novel To Kill a Mockingbirg, Burris Ewell is the son Bob Ewell and, like the rest of his family, is somewhat lacking in the finer points of personal hygiene.  He is first introduced to the reader in Chapter Three, when his and Scout's teacher, Miss Caroline, suggests he go home and clean up.  Scout, the novel's narrator, describes Burris, and the scene in the classroom, as follows:

The boy stood up. He was the filthiest human I had ever seen. His neck was dark gray, the backs of his hands were rusty, and his fingernails were black deep into the quick. He peered at Miss Caroline from a fist-sized clean space on his face. No one had noticed him, probably, because Miss Caroline and I had entertained the class most of the morning.
“And Burris,” said Miss Caroline, “please bathe yourself before you come back
tomorrow.”
The boy laughed rudely. “You ain’t sendin‘ me home, missus. I was on the verge of leavin’—I done done my time for this year.”
Miss Caroline looked puzzled. “What do you mean by that?”
The boy did not answer. He gave a short contemptuous snort.

Burris is not only representative of his family in terms of hygiene, but also in terms of disregard for authority and primitiveness in his world outlook.  His father, of course, is the town's leading racist and slob.