Just this week, our guild had a speaker who shared feed sacks and their history. (She has had over 10,000 - a collector of all sorts of things related to feed sacks.) They were made from the mid 1800's until sometime in the 1960's. Some she showed were paisley. So it could be...Your family research is probably more correct, as cotton was the fiber of choice for the feed sacks. I'll bet similar fabrics could be found somewhere. I've seen something like them at goodwill...
I'll be waiting to see your reproduction. The original reminds me of some my grandmother made. (What happened to them is more than I know.) Definitely utilitarian. Much used. Much loved.