Eat crow

Eating crow is the American equivalent of having to eat humble pie, where one has to admit one’s mistake, recant, and sometimes atone. To eat crow dates from the mid-19th century. There are two theories about the origin. The first is from the allusion to the flesh of a crow, a carrion-feeding bird that is very unpleasant to eat. The second is that it derives from crow meaning the intestines of an animal, which the OED dates from the late 1600s. Both theories revolve around the fact that having to eat something grossly unpleasant is a humiliating experience. Most American sources favour the first theory, and since the expression originates in America, this is probably sufficient evidence for it to be valid.