Pre-washed muslin or onasburg fabric is what I use for backings on hangings I put on my screened in porch. I also use the onasburg for sample machine embroidery designs, backings on table runners, coasters, etc. It is a surprisingly versatile fabric, introduced to me by a local quilt shop owner. It is inexpensive and quite durable, and easy to work with. It has more "body" than muslin and I especially like it for the backings on wall hangings.
https://www.fabric.com/buy/0342283/roc-lon-preshrunk-osnaburg-natural