Keep the carrot tops for homemade stock, to feed your pet rabbit or to stuff inside a whole chicken/turkey when roasting.
Any root veggies that are in season can be used in this dish so buy what looks good and you family likes i.e. turnips, rutabaga, sweet potatoes or yams.
The mushrooms I added in the last ten minutes of cooking could be replaced with almost any quick cooking veggie like Brussels sprouts, cauliflower, or asparagus.