Flour

Rye flour can only be obtained through trade at a village bakery or granary. These bags weigh 12 lbs, and can be used to produce either flat breads or porridge. 1 bag of rye flour can produce about fifty flat breads, or many servings of porridge using the cookery skill.

It is worth noting that rye flour does not spoil, and can thus be used as an "emergency food store". This is not true for the foods made from it however, so you should take care to not make too much at one time.