Simmer vinegar, peppercorns and bay leaves in a small covered saucepan 10 minutes over medium-low heat.
Bring to a boil over medium heat.
In a large saucepan, combine water and salt; bring to a boil.
Cover tightly and simmer over low heat 10 minutes.
Strain mushrooms; discard cooking liquid.
Let cool. Arrange equal amounts of mushrooms in pint canning jars.
Pour boiling marinade over mushrooms to cover.
Place lids on jars; seal tightly. Let cool to room temperature; refrigerate.