This Canadian Food Board poster from WWI discourages the hoarding of food and points out that fines and/or jail time are possible punishments. 'Are you breaking the law? Patriotic Canadians will not hoard food.
11 great posters from when we used to care about wasting food
This is a propaganda poster regarding food rations during the time of World War I. The posters would say "Food is a weapon, don't waste it" meaning that food is scarce just like the weapons we need for war.