I acquired for free 12 big flats of white button mushrooms. They are still in fine shape and over the last couple of days I have been eating everything with mushrooms but obviously I'm going to have to do something with these in the next few days. I don't have a pressure canner at the moment so I'm going to have to freeze them I guess. Is there some particular way I need to prepare them or freezing? Just wash or brush them and freeze them? I want to make sure before I do it as I don't want to wreck 100 pounds of mushrooms. Any ideas would be greatly appreciated.