Winline has a great selection of battings. I like their 80/20 better than Warm and Natural (which we're led to believe is 100% cotton, but isn't). Winline also has an awesome 100% cotton batting.
https://www.winlinetextiles.com/ There's also a list of retail stores around the country who carry their batting.
https://www.winlinetextiles.com/retail-stores-s/106.htm