Place wheat berries in a bowl; cover with plenty of water (berries will absorb some) and let stand 8 hours or overnight.

Drain wheat berries and place in a Dutch oven or large saucepan with 6 1/2 cups water. Bring to a boil; stir in mushrooms. Reduce heat and simmer, covered, 20–25 minutes or until tender. Stir in 1/2 teaspoon salt.

Heat oil in a large nonstick skillet over medium heat. Add onion, celery, and carrot. Cook for 10 minutes or until vegetables are nearly tender. Stir in garlic and cook 1 minute. Add vegetable mixture to pot with wheat berry mixture. Stir in remaining 1/2 teaspoon salt, beans, rosemary or thyme, and pepper. Let simmer 4–5 minutes to allow flavors to blend. Stir in parsley, plus salt to taste, and serve.