As a general guide, mushrooms found in the wild should only be cleaned with a soft brush to remove any soil and then wiped with a damp cloth. Mushrooms purchased in markets or shops—grown in humus that may not be as natural as that in the woods—should be dunked and swished around quickly in a few changes of very cold water, drained well, and patted dry with paper towels. Wait to do this until just before cooking, and do it quickly to keep them from absorbing any liquid. Because of their irregular honeycombed surface, morels may need more attention with a brush and damp cloth to remove any grit.