I have picked them as late as Thanksgiving around Forks. They were pretty hammered for the most part. Sometimes you can find some that are hiding in or under big stumps. I have found some really nice nice ones that were basicaly "hiding" from view. Be sure to look in stumps.

If you find heavy, wet ones, a few days on newspaper or paper towels under a fan works pretty well. You will get some that turn brown or rotten and be sure to keep an eye out for mold.

I think that once you get a hard frost, it is pretty much over.