There are many good books written about mushrooms, and you can easily find find guided mushroom tours in your area.
A golden rule, though! Never eat wild mushrooms, unless you are absolutely sure what they are.
You need to clean the mushrooms before you cook with them. The best thing to do if you are out picking your own mushrooms, is to clean the as well as you can as you pick them.
Cut of the base of the stem and brush as much of the dirt off as you can. This makes it much easier when you get home in the kitchen.
A mushrooms is essentially a sponge, so therefor you should use as little water as you can when you clean them. I usually only use a brush, utility knife and a damp cloth for the tough bits.
If you use to much water, the mushrooms tend to splat out on the pan and looses a lot of their flavour.
Girolles can sometime be really difficult to clean. The dirt can easily get into the ridges, so it’s extra important to clean the as yo pick them.
If you get some girolles, that are too difficult to clean the proper way. Leave them to soak i cold waster for 5 minutes, spin the in a salatspinner and leave the to dry on a clean tee-towel.