De-stem mushrooms, quarter onion and cut up bread. Add all to food processor and pulse until fine.
Melt butter in skillet. Add mushroom mixture and saute 5 minutes. Add lemon juice, parsley, salt, marjoram, thyme, garlic and white wine, Mix well and saute 5 minutes over low heat.
Place mushroom caps in a 9" x 13" pan and sprinkle with salt. Fill caps with mushroom mixture.
Bake at 375-degrees for 10 minutes. Turn oven to broil and move to 4-5 inches from heat. Broil 5 minutes.