I think any allergens from the mushrooms would be washed out of your clothes. If you don't mind me asking -- have you had a contact-type allergic response to wild mushrooms in the past?
“Think occasionally of the suffering of which you spare yourself the sight." ~ Albert Schweitzer C/F temp conversion
Name: greene Savannah, GA (Sunset 28) (Zone 8b) I have no use for internet bullies!
I re-read the original question. You asked about stepping on the mushrooms in the winter - we have no idea where you are living. Perhaps if you would take a few moments to complete your profile page to include your location we might give you better answers for any toxic mushrooms that may grow in your area.
Sunset Zone 28, AHS Heat Zone 9, USDA zone 8b~"Leaf of Faith"