Heat margarine in Dutch oven over medium-high heat. Cook celery and onion in margarine about 2 minutes. Remove from heat.
Stir in remaining ingredients. Depending on how moist you want the stuffing, use more or less of the vegetable broth.
Transfer to a 2-quart casserole. Bake at 375 degrees for about 35 minutes.
For apple-raisin: Increase salt to 1-1/2 teaspoons and add 3 cups finely chopped apples and 3/4 cup raisins.
For mushroom: Stir in 2 cups fresh sliced mushrooms with celery and onion.