Dried mushrooms are one of those conveniences that, once you start using them regularly, it's hard to remember how you did without. Fresh mushrooms can have a delicate flavor that takes some coaxing to bring out, but when they're dried the aroma intensifies, and when rehydrated with hot water, the soaking liquid becomes a concentrated umami broth while the flesh becomes meaty. The most common are shiitakes, porcini, chanterelle and morels.
Toss a few dried chanterelles to your stock to add a level of flavor complexity, or use the porcini and its soaking liquid in a creamy risotto. Consider adding a few dried mushrooms to a pasta sauce or soup—and then removing the mushrooms themselves before serving. What's left behind is a hint of deep umami. One of the simplest and easiest uses is to grate the still-dried mushrooms using a microplane. They end up looking like snowflakes on a plate.