In addition to food stuffs don’t forget the “barterables”. ATF = alcohol, tobacco and firearms. With UN troops occupying American cities during a famine I’m sure a pack of cigarettes and a quart of whiskey could buy you a weeks worth of food.
One of the most useless things is gold. In the very early stages of a crisis, gold may have high value but when it becomes evident that civilization has collapsed, someone will give me a lot of gold that they can't eat, for a peanut butter sandwich that they can eat.