I use vegetable stock quite a bit when cooking. In fact, it’s the only kind of stock we always have handy. It’s easy to make, and you can make it quite often if you’re in the habit of saving your vegetable scraps.
We save bits such as green onion tops, celery ends, and mushroom stems, keeping them in a gallon bag in the freezer. (I’ve also been known to just chop up several celery stalks from a fresh bunch and throw them in the bag, because you can’t buy just one stalk and we rarely need more than two at a time for any of our recipes.)

Once the bag’s, say, three-quarters full, you’ll have the makings of a good vegetable stock. (You can also add these scraps to a meat stock, of course, but we don’t usually have bones handy when have enough vegetables!) We do sometimes need to supplement the bag with extra quartered mushrooms, or more onion, but we pretty much always have those items around anyway.
For easy (and lazy) stock making, you can just throw your vegetable scraps in a crockpot with some peppercorns, salt, a bay leaf or two, a couple of garlic cloves, herbs like rosemary or thyme if you’ve got them, and enough water to cover.

Use the low setting, if your crockpot has more than one. Cook for several hours (I often start it in the morning and don’t stop it until after dinner). Strain, cool, separate into storage containers, and freeze.