On work surface lightly sprinkled with flour, roll pie crusts to about 14x10 inches each. Using knife or pizza cutter, cut around edges to create fish shapes that are both same size. Arrange salmon on 1 crust. Top with mushroom mixture. Brush around edge of crust with beaten egg. Top with other crust. Fold edges over; pinch to seal. Using spoon, make slight indentations to look like scales. Using extra crust pieces, roll a small piece for an eye and fins, pressing in place.