Season meat with salt and white pepper and dredge with flour. In hot skillet, cook bacon pieces about half way. Add rabbit and/or pheasant and brown on both sides. Add onions and saute with meat. Add mushrooms. Pour beef stock over all and put in preheated oven at 450 degrees for 30 minutes, or until meat is done. Take meat out. Whip sour cream into remaining pan juices and pour over meat.