When I've gathered enough ingredients, I throw on a pot of stock. You can make any of the following stocks more intense in flavors by simply simmering them for an extended period of time until their liquid volume is reduced. Of course, you can always buy canned stock. I predict, however, if you try making your own, you'll never go back. The flavor will vary slightly, depending on the mix you use.
Some people feel that asparagus also overwhelms the stock.
I personally don't agree, and find that asparagus adds a depth and richness to vegetable stock. Making vegetable stock is a great way to clean out the refrigerator of food that is less than fresh, don't limit your stock making ingredients to whole vegetables. Your stock will be strained before being used, and all those unattractive peels will be gone, but they will have imparted a lovely flavor to your stock. You can also add some fruit or fruit scraps to your vegetable stock ingredient mix. Apples, pears and even pineapple works well.