there is a type of cotton weave, like what is used with bandages, that is knotty and tangled and even without adding elastane or other stretchy rubbery synthetic crap, has a lot of stretch. you can also, a bit more expensive, just get a very large piece of medium weight canvas and cut it across the bias (45 degrees) and it has a lot of stretch in this direction, but is more durable than bandage weave. also, it's possible to use wool, which is also a naturally elastic material, even silk, when woven, if you cut across the bias, but knitted is better, and it is possible to find heavier knit fabrics, they are stretchy across the "weft" if you can call it that.