In a medium saucepan, cover the soaked beans with 2 inches of water. Add 1 bay leaf, the thyme sprig and the whole garlic clove and bring to a boil. Cook over moderate heat until the beans are barely tender, about 20 minutes. Drain the beans and discard the bay leaf, thyme sprig and garlic.
Preheat the oven to 350°. Heat the olive oil in a medium enameled cast-iron casserole. Add the rice, barley and wheat berries and cook over moderately high heat, stirring constantly, until lightly browned , about 10 minutes. Add the onion, minced garlic and thyme leaves and cook, stirring, until the onion is softened, about 5 minutes. Stir in the tomatoes, olives, beans, broth and the remaining bay leaf and bring to a simmer over moderately high heat.
Cover the casserole and bake for 50 minutes, or until the liquid is absorbed and the grains are tender but still slightly chewy. Let stand for 10 minutes, then remove the bay leaf. Stir in the scallions and butter and serve.
One Serving Calories 282 kcal, Total Fat 5.7 gm, Saturated Fat 1.4 gm, Protein 9.4 gm, Carbohydrates 49.4 gm.