Storage options for Oyster mushrooms
I haven't tried this myself but upon researching on the web, there are several ways that you can preserve mushrooms: (please click the sub headings for reference)

Freezing mushrooms - 


  Freezing your mushrooms will allow them to keep their great flavour,
  but freezing leaves you with a soggier looking mushroom. Frozen
  mushrooms are ideal for soups, stews and casseroles.
  
  Using the method below your mushrooms should keep for about a year.
  
  
  Bring 1 l of water to the boil with ½ a teaspoon of salt.
  Add mushrooms and bring to the boil again.
  Boil for another 3 minutes.
  Rinse with cold water.
  Drain thoroughly.
  Seal in freezer bags.
  Freeze.
  


Dehydrating mushrooms


  Stored properly, dried mushrooms have a more potent flavour than fresh
  ones, so you will use less dried mushrooms vs. fresh.
  
  Directions for Drying
  
  
  Pre-heat your oven to 150°.
  Slice your mushrooms into slices about ½ cm. The thicker the slices, the longer they take to dry out.
  Arrange your sliced mushrooms on baking trays in a single layer.
  Bake your mushrooms for 1 hour and remove from oven.
  Use some paper towel to gently dab any moisture that sweated out from your mushrooms.
  Turn your mushrooms over and cook for another hour.
  By now your mushrooms should be completely dry. If not, repeat Steps 4 and 5 until they are dry.
  Allow them to cool, and then store them in an air-tight container in a cool, dark place.
  
  
  Your mushrooms are ready to store when they feel dry when you touch
  them. They should still be flexible A good idea is to add a wad of
  paper towel at the bottom of the jar - just to absorb any moisture
  that might still be lurking around.
  
  To Rehydrate Put your mushrooms in a bowl of warm water for 30 minute
  or if you are in a hurry, bring a pot of water to the boil and simmer
  your mushrooms for 10 minutes Keep this liquid for stocks, soups and
  sauces by pouring the liquid into an ice tray and freezing. When you
  need it, just pop the frozen stock into the pot.