An example of an endospermous seed is "maize grain."
Endospermous seeds are those that have a food storage tissue called "endosperm" that nourishes the developing embryo of the seed. In the case of maize grain, the endosperm is the starchy part of the seed that we eat as cornmeal, cornstarch, or popcorn.
During seed development, the endosperm is formed when the female reproductive cell (the egg) is fertilized by the male reproductive cell (the sperm). The endosperm provides nutrients for the embryo until it is able to photosynthesize on its own after germination.
Cashew nut, cotton seed, and bean seed are not examples of endospermous seeds, as they have different mechanisms for storing and providing nutrients to the developing embryo.