Are you sure, MultiMedea? I mean, Brer Fox and Brer Bear are also called that. I always thought "Brer" meant "Brother."
But yes, in the Uncle Remus stories, the thorny thing is spelled "briar." I'm pretty sure, anyway. I think that's where I got used to seeing the word spelled that way. I read all those stories as a child. Heck, I read anything I could get my hands on that had talking animals.