I keep a bag in my freezer to save vegetable scraps… celery and carrot trimmings, parsley stems, onion bits and skins (yes, the skins go in too… adds color!) mushroom stems, etc. That way I’ve always got a good (and cheap!) supply of veggie bits to throw into the pot if I want to make some stock. Then when the stock is done, I boil it down and freeze it in ice cube trays… saves space and lasts longer, and I can grab as much or as little as I need.