1.In A Large Skillet, Saute Mushrooms In 2 Tablespoons Butter Until Tender. Stir In Parsley. Remove Mushrooms To A Serving Platter; Keep Warm. Combine Flour And Salt In A Shallow Dish; Coat Fillets With Flour Mixture On Both Sides. Add 2 Tablespoons Butter To The Skillet. Cook Trout Over Medium Heat For 8-10 Minutes On Each Side Or Until Fish Flakes Easily With A Fork; Arrange Over Mushrooms. 2.For Sauce, Melt Remaining Butter In A Small Saucepan. Gradually Stir In Cream And Lemon Juice. Bring To A Boil For 3-4 Minutes Or Until Slightly Thickened, Stirring Constantly. Serve Over Trout And Mushrooms.