Children will hardly notice the spinach in these tasty sesame-seed-specked rice balls.
Put rice in a medium saucepan, and cover with 1 3/4 cups cold water. Bring to a boil. Stir once, and reduce heat to low. Cover, and cook until rice is very soft, about 40 minutes. Remove pan from heat. Let stand, covered, 5 minutes. Stir in spinach and sesame seeds. Transfer to a medium bowl. Let stand until cool enough to handle, about 10 minutes.
Using damp hands, shape mixture into 1 1/2-inch balls. Serve warm or at room temperature.
Rice balls can be refrigerated up to 3 days. To reheat, bake at 350 degrees until heated through, about 10 minutes.