I think I may be being a bit dim here

just making dinner and the mushrooms that admittedly I bought before Easter and had put in the larder were all shrivelled up, (still used them though). Was wondering surely it can't be this easy to dry mushrooms?
Whenever I have actually gone out gathering mushrooms I have always frozen them. We sometimes buy dried mushrooms which are really expensive and it just got me wondering. Anybody got any ideas please
