In a skillet, cook chicken in butter 3-4 minutes on each side. Place chicken in a bowl and combine with cream cheese, mushrooms, onion, salt and pepper.
Unroll dough. Place mixture onto each piece of dough and fold the three corners up, like a pocket. Pinch edges to seal. Bake, uncovered, at 350 degrees F for 20 minutes or until crescents are golden brown.