Big honking bag o' mushrooms

Someone just gave me a big honking bag of mushrooms, because they know I like to cook. I’m not sure what kind they are, but later today I could post pictures of them if necessary. It’s a large Ziploc bag full of the little guys (white, and somewhat the size of a plum).

What could I do with 'em?

If you don’t know the identity, how about the person that gave them you you? Are they a reliable source? Are they wild or cultivated?

Mmmmm, mushrooms!

Chop some up and toss them into a salad
Saute in butter and olive oil and pile on top of a juicy steak
Make a spinach and mushroom omelet
Make a big pot of homemade cream of mushroom soup
Bake a brown rice pilaf with mushrooms casserole