In a 4-quart Dutch oven, cook and stir celery, onion, and wine over medium heat for 5 minutes. Add mushrooms; cook and stir 5 minutes more.
Add vegetable broth and bring to boiling. Add wild rice. Reduce heat. Simmer, covered, for 30 minutes. Add quick-cooking rice. Simmer, covered, 10 minutes more or until rice is tender and broth is absorbed. Transfer rice mixture to a large serving bowl. Season with salt and pepper to taste. Gently stir in mandarin oranges and walnuts. Makes 8 to 10 servings.