Food Ration is an important item, which can be obtained in many different ways. Mainly through Expeditions or trading, But can also be obtained the Planter and the Auto Pantry. Traps and cannibalism yield meat instead, which must be stored in a freezer. When you bring Food Rations home, they will be stored at a pantry, where you can eat it to fill the hunger need.
Unlike most items, Food Rations are not stored in the shelter inventory but instead in pantries. It can be traded with if a visitor arrives at your shelter to trade however expeditions cannot take some Food Rations with them from the shelter when departing.