A food ration is the most basic comestible in NetHack. Many roles start out with a number of these. Samurai know them as gunyoki. They provide enough nutrition to fill you when you are hungry. They are also suitable for vegans.
Note that a lembas wafer provides the same nutrition as a food ration but is much lighter.
The little girl stood on tip-toe and picked one of the nicest
and biggest lunch-boxes, and then she sat down upon the ground
and eagerly opened it. Inside she found, nicely wrapped in
white papers, a ham sandwich, a piece of sponge-cake, a pickle,
a slice of new cheese and an apple. Each thing had a separate
stem, and so had to be picked off the side of the box; but
Dorothy found them all to be delicious, and she ate every bit
of luncheon in the box before she had finished.
[ Ozma of Oz, by L. Frank Baum ]
Encyclopedia entry (gunyoki)
The samurai's last meal before battle. It was usually made
up of cooked chestnuts, dried seaweed, and sake.