Hi Leisha,
we sell our mushrooms to shops and restaurants in the all too familiar (blue/ black) plastic trays (you’ll see a lot of them used by veg shops/ wholesalers). What we do is use these again and again.
The way we keep the mushroom fresh is by putting a layer of kraft packing paper with a bit of water sprayed on. The same when you cover it over and then keep it in fridge.
Hope that helps and happy selling 🙂
Eric