Pull off stems and cut off any brown spots. Discard or add to compost pile.
Soak in cold water for 10 minutes to loosen any dirt then wash mushrooms in clean, cold water.
Cut large mushrooms in halves, quarters, or slices. Leave small mushrooms whole, if desired.
Cook
Put mushrooms in a large pot and cover with water. Bring to a boil. Boil for 5 minutes.
Can
Pack hot mushrooms into hot pint or half-pint jars leaving 1-inch of headspace. Add salt (optional) ¼ tsp. per half-pint, ½ tsp. per pint. Top off with liquid from pot leaving 1-inch headspace.
Remove bubbles from jars and adjust headspace if needed. Wipe jar rings and add lids and jar rings.
Process in a pressure canner at 10 lbs weighted gauge or 11 lbs dial gauge for 45 minutes. Adjust pressure for altitude if necessary.
Check lids and allow jars to fully cool before storing.