The recipe on a box of stuffing mix usually calls for 1/2 cup chopped celery and 1/2 cup chopped onion, along with a good chunk of butter. A few nights ago I tried an experiment: I cut the butter way down (just about 2 tsp.) and used 1 cup minced carrots, 1 cup chopped onion, and 1 cup chopped celery (and then followed the recipe as stated).
It was great! Better than usual! And so much better for us. :)