I've used flannel as a backing but never homespun. I did,however, use homespun and a light weight flannel in the first ever rag quilt that I made.

I am not one who really likes mixing any cotton fabric with flannel. Even with pre-washing, I found out too late with my project that they didn't mix well. It was a dog quilt.

Don't know if this is just in the states, but here homespun is a loosely woven fabric, usually 100% cotton. I've never seen it in a print, always a solid, woven plaid or woven stripe, and usually in 'prim' colors: tans, browns, dk blues, maroons... good for rag quilts as it ravels easily.