TO WASH OR NOT TO WASH?
Don't wash Mushrooms with water as this will put extra moisture into them. Instead wipe them over with a bit of kitchen towel or a clean dry toothbrush to remove any dirt or soil.
SHOULD YOU USE THE STALKS?
As a general rule leave the stalks on for slow cooking but remove them for quick fast cooking.
Heat some olive oil and butter in a frying pan and put in a handful of whole Mushrooms. Do not move them around but cook them until begin to "squeak" to let all of the water evaporate before tossing the pan. You can add some chopping garlic or herbs to the Mushrooms for flavour.