1. Bring a medium saucepan of water to a boil, and add 1 teaspoon salt. Stir in rice; reduce heat, and simmer for 15 minutes (rice will not be done). Drain. Set aside.
2. Place porcini in a medium bowl; add 3 cups hot water. Let stand 15 minutes. Drain through a sieve over a bowl; reserve liquid. Chop porcini.
3. Heat 1 tablespoon oil in a large skillet over medium-high heat. Add sliced fresh mushrooms; sauté for 8 minutes or until moisture evaporates and mushrooms begin to brown, stirring occasionally. Stir in reserved porcini, green beans, 1/4 teaspoon salt, and 1/4 teaspoon black pepper; cook for 2 minutes or until the green beans are crisp-tender. Place mushroom mixture in a large bowl; keep warm.
4. Return pan to medium-high heat; add remaining 1 tablespoon oil. Add shallots, and sauté 4 minutes or until tender. Add rice; cook for 2 minutes, stirring occasionally. Stir in remaining 1/4 teaspoon salt and 1/4 teaspoon black pepper. Stir in wine; cook 2 minutes or until the wine evaporates, stirring constantly. Add 1/2 cup reserved mushroom liquid to rice mixture; cook 3 minutes or until the liquid is nearly absorbed, stirring constantly. Stir in remaining mushroom liquid, 1/2 cup at a time, stirring constantly until each portion is absorbed before adding the next (about 30 minutes total). Stir in mushroom mixture, Parmigiano-Reggiano, and parsley; sprinkle with thyme. Serve immediately.