Button mushrooms and orange juice add zest to this rice side dish.
Bring a medium saucepan of water to a boil. Add rice, and simmer until tender, 20 to 25 minutes. Drain; set aside.
Prepare vegetables: Heat oil in a large saucepan over medium heat. Add onion and celery; cook until softened, about 10 minutes. Add mushrooms; cook until softened, about 5 minutes. Stir in cooked rice, scallions, zest, and juice. Season with salt and pepper. Serve warm or at room temperature.