DH doesn't like mushrooms, so I often have to keep them for a while. I learned from Rock Lobster (why won't the forum software bring up his username when I type @ and the start of his username?) to make sure that mushrooms are taken out of those baskets with plastic wrap as soon as you get home. Put them in the fridge in a way that will get them lots of air. They may get dry, but that's still usable or you can dry them all the way. They almost never just go off.