Maybe you lucked into a big foraging haul (I'm still finding oyster mushrooms even in February) and it's way more than you can use fresh. Or maybe you've got some supermarket mushrooms in your crisper drawer and they're going to get slimy if you don't do something with them soon.
Either way, drying mushrooms is a good solution. Rehydrated, they are just as flavorful and tender as they're fresh counterparts. They are also one of the quickest-to-dry foods.