sweetbreads 
Designates the tender, delicately flavored thymus gland of calves, lambs and kids; veal sweetbreads are especially prized.
liver 
People eat the liver of slaughter animals, poultry, game and some fish (cod); it has a high iron content.
heart 
Cooked in ragouts and casseroles, it can also be sautéed, roasted, braised or simmered; veal, lamb and chicken heart are the most popular.