Wiktionary
n. A plastic wrapper in which a loaf of bread is sold, intended to keep the bread fresh for longer than it would be if unwrapped.
Wikipedia
Bread bags or ration bags are small to medium sized bags issued to soldiers to carry their rations. Often, such as in the case of Swiss and World War II German designs, they will have straps for attaching to belts and/or bikes. They can be commonly found in the military surplus market and are often bought by collectors and people finding new uses for them.
Usage examples of "bread bag".
The picnic tables in the grassy area had been abandoned except for a foursome of gulls squabbling over a bread bag that had been tied shut and left on the edge of a trash bin.
Only then could they drink their fill from the waterskins, help themselves from the bread bag and cut slices of dried meat from the provisions they found.
Nikki had a bread bag in her hand and she tossed them some crumbs.
Breaking the spell, she looked to see it was safe, then reached into the bread bag and took two braided loaves.
Nevertheless, we gathered them into the bread bag we had brought to carry back the birds.
Ukiah got a fresh diaper onto Kittanning, strapped him back into his car seat, and dropped the diaper into the bread bag, which he tied shut, effectively enclosing most of the foul odor.
He found the bread bag, glad to see there were plenty of round crusts to eat.