In large skillet, cook ground beef and onion until beef is thoroughly cooked and onions are tender. Drain. Stir in ketchup and mustard.
Separate biscuit dough. On ungreased baking sheet, flatten biscuit dough to form 6-inch rounds. Spoon beef mixture onto one side of flattened dough. Sprinkle with cheese. Top with dill pickle half. Fold dough over filling. With fork tines, press dough edges to seal. Cut two slits in top of dough to release steam.
