Boil cleaned & chopped mushrooms for 5 minutes. Drain.
Pack boiled mushrooms into sterilized jars.
Add salt, 1/4 teaspoon per 1/2 pint.
Fill each jar with boiling water, leaving 1/2 inch headspace.
Wipe jar rim, fit with 2 part lids and lightly snug.
Place on a rack in your pressure canner, add water.
Can under high/10psi pressure for 40 minutes.
Naturally depressurize. Remove from pressure canner, allow to cool at room temperature for 24 hours before removing rings. Discard any jars that did not seal.
Notes
Wild mushroom canning safety note: This card records my personal kitchen practice, not a tested canning recommendation. The National Center for Home Food Preservation says not to can wild mushrooms. Its published process is for domestic mushrooms, not wild maitake. My experience and a sealed lid do not establish safety; improper canning can cause botulism. For a recommended option, freeze or dry positively identified edible mushrooms instead. Read the full safety note at the top of the article.