Heat oven to 375°F. In medium saucepan, combine chicken, soup, green beans, mushrooms, cheese, mayonnaise and lemon juice. Bring to a boil, stirring occasionally. Pour hot chicken mixture into ungreased 13x9-inch baking dish.
Separate dough into 8 biscuits; arrange over hot chicken mixture. Brush each biscuit with margarine; sprinkle with crushed croutons.
Bake at 375°F. for 23 to 27 minutes or until deep golden brown.