To save them for future use, I chose to dehydrate them. They take up less space to store and you can easily pick out how many you want, right down to the last piece.
According to the authority on dehydration (Colorado State University) you should scrub the mushrooms and discard tough, woody stalks. Slice tender stalks 1/4” thick, peel large mushrooms and slice. Leave small mushrooms whole. Dip in a solution of 1 teaspoon citric acid per quart of water for 10 minutes. Drain, then dry 8-12 hours until dry and leathery.
After reading the information I decided that while cleaning dirt off the mushrooms was important to me, scrubbing them was not. If they got wet from cleaning, I dried them with a towel (I'm not going to put something WET into the dehydrator!) before slicing them. Since I wanted them all sliced I skipped that other step too. What I would stress to you is slicing them all an even thickness. You want them all thoroughly dehydrated before storing them. The citric acid soak wasn't important to me - it's mostly to keep them from discoloring and that has never been an issue.
Next step is getting them on the dehydrator. My nice big stainless steel dehydrator does not have small enough openings in the trays to keep the mushroom pieces from falling through. Thank goodness for the old stand-by that served us for many, many years! I set the temperature around 140 degrees and went to bed. By morning there was progress, but it wasn't done. A few hours later it had reached that dry and leathery stage. Remember than the temperature and humidity in your home will influence this timing.
The end result: 2 quart jars of dehydrated mushrooms ready and waiting for whenever I need them. It just doesn't get much better than that.
RECAP
1. Clean and dry
2. Slice
3. Place on dehydrator @ 140 degrees Fahrenheit
4. Remove when dry and leathery
5. Store in airtight jars