Very old heavy cotton feed / seed sack, an Atlas (Bemis type) bag, about 40" long x 20" wide, still sewn up as a sack.
This is right out of an old dairy barn here in Wisconsin, and looks - and smells! - it. We haven't washed it, but would expect it would improve with a good soaking.
It's very rough, with stains and holes and / or patches and darning, with marked names or initials of former owners. It's a beautiful authentic old American country primitive just as it is.