Yes you can freeze fresh mushrooms to preserve them.
To freeze fresh mushrooms it's best to quick freeze the fresh mushrooms first on some parchment paper that is lining a tray.
Place the fresh mushrooms on the parchment paper lined tray and then quick freeze them.
After you quick freeze the fresh mushrooms then place the mushrooms in freezer bags and remove all the air you can out of the freezer bag.
Removing the air prevents the mushrooms from going bad in the freezer.
Airtight freezer bugs or airtight freezer safe containers work great for freezing fresh mushrooms.
The mushrooms will last in the freezer for 6 months to a year before they go bad.