Tear the white bread and cornbread into chunks.In a large bowl, combine the bread chunks, onions, celery.Pour the melted butter over the bread, onions, celery, and stir.In a separate bowl, beat the eggs, and stir in the chicken broth, salt and pepper.Pour the egg and broth mixture over the bread/ celery/ onion mixture, and stir to combine.Transfer to casserole dish that has been greased or sprayed with cooking spray.Bake at 375 for about 45 to 50 minutes minutes.