For the green “rind,” add 4 cups of cereal into large bowl and set aside. Melt 4 cups marshmallows and 3 tablespoons butter in a microwave-safe bowl for two minutes, or on the stovetop until puffy. Remove from microwave or stove and stir in a drop at a time of green food coloring until desired color. Pour green marshmallow mixture over the bowl of cereal. Quickly stir together using a buttered spatula.