About two hours before serving: In a large bowl with mixer at medium speed, beat cream cheese, 1 1/2 cups of flour, and 1/2 cup margarine until smooth; Shape into ball, Cover and refrigerate 1 hour.
Meanwhile, in 10 inch skillet over medium heat cook mushrooms and onions in 3 tablespoons margarine until tender, stirring occasionally. Stir in sour cream, salt, thyme and 2 tablespoons flour; set aside.On floured surface with floured rolling pin, roll 1/2 of dough 1/8 inch thick.With floured 2 3/4 inch round cookie cutter,cut out as many circles as possible. Repeat. Preheat oven to 450 degrees.When mushroom mixture cool, combine with cream cheese mixture. Onto 1/2 of each dough circle, Place a teaspoon of mushroom mixture. Fold dough over feeling. With fork, firmly press edges together to seal; prick tops. Place turnovers on ungreased cookie sheets. Bake 12 to 14 minutes until golden. Makes about 3 1/2 dozen.