Called 'bread bags'. The webstaurantstore, has them.
https://www.webstaurantstore.com/search/bread-bags.html
You might read through the 'art of growing micro greens' posting.
Curtis Stone on y-tube has 5 or so good videos just about growing
microgreens. Most valuable info I have found.
I grow all winter. Here is some radish mix in the middle, peas on the left.