@ehBeth,
well, I washed em n did the experiment. It true, the mushroom doesnt take on anu water after washing and it about the same brushing or washing. SO , going for the better idea for removing compost from the mushroom cap, Ill wash em.
The "baby bell'" were teeny portabellas (Which is a made up name anyway), and ,along with some criminis , which have meatier taste but are a bit tougher, we had a nice side dish of sauteed mushrooms and caramelized onions.
Now I need advice on speeding up the caramelization process without burning.
..........
Osso, Im not sure I want to freeze caramelized onions, they are so delicate freezing may yield a mushy mass of onions.