Before going out to Camber's garage with Tad, Donna packs a lunch box (in my book it's on page 142 -- King doesn't use chapters in Cujo). She wraps green olives and cucumber slices in foil. Later, when they eat the food (page 165) she is "holding the Tupperware dish with the olives and slices of cucumbers inside, each wrapped neatly in Saran wrap".