Lady Bird's group leave Big Bend for Fort Davis; Lady Bird takes photos of scenery; Lady Bird meets Nellie Connally and Ben Barnes at Fort Davis; Lady Bird meets two Native Americans & two Vietnam soldiers; Lady Bird views museum exhibits; Lady Bird gives speech at ceremonies; Lady Bird departs for the LBJ Ranch; Lady Bird, Stewart Udall and others view proposed park area at the LBJ Ranch; visits to West and Scharnhorst Ranches