Natural fibers, for sure. I would think any heavy weave fabric would work. You could look for an antique style flat weave carpet, but it will cost you unless you are lucky enough to come across a very worn old piece at an estate or garage sale.
Yup Family Heirloom for sure. There's also a fabric/hobby/sewing store in Gettysburg that seems to always have everything. Having a massive brain fart and can't remember the name of the place.