Cook millet: Bring 1 cup millet and 2 1/2 cups water to a boil. Cover and reduce heat to medium. Cook for 15 minutes. Remove from heat and let sit uncovered for 20 minutes.

In a mixing bowl, combine cooked millet, chopped yellow onion, chopped white mushrooms, beaten egg, beaten egg white, garlic powder, dry parsley, and ground black pepper.

Gradually add dry bread crumbs, stirring constantly, until the mixture is firm enough to form into balls.

Wet hands and shape the mixture into balls, using about 1 1/2 tablespoons per ball.

Simmer the meatballs in marinara sauce for 30 minutes, or bake on a lightly oiled baking sheet at 325 degrees Fahrenheit for 30 minutes.

Serve hot with marinara sauce.