Heat oven to 400°F. In 10-inch skillet, cook sausage, apple, celery and onion over medium heat 8 to 10 minutes, stirring occasionally, until sausage is no longer pink and vegetables are tender; drain.
Roll each biscuit into 4 1/2- to 5-inch round. Spoon about 2 tablespoons sausage mixture on half of each round. Fold other half over filling; press edges with fingers or fork to seal. Place on ungreased cookie sheet.
Bake 12 to 15 minutes or until golden brown. Serve warm.