Steam cook them for about 5-10 minutes, or until all the blue coloring is gone. Let them dry again or eat them as is.
SWIM found that steam cooking old dried mushroom will make them far more potent. I don't know why, but it does.
SWIM has done this to 10 year old dried mushrooms kept in a plastic bag, not air tight, and they worked just fine after steaming them.
You may remember me as 69Ron. I was suspended years ago for selling bunk products under false pretenses. I try to sneak back from time to time under different names, but unfortunately, the moderators of the DMT-Nexus are infinitely smarter than I am.
If you see me at the waterpark, please say hello. I'll be the delusional 50 something in the American flag Speedo, oiling up his monster guns while responding to imaginary requests for selfies from invisible teenage girls.