Ralph B. Clark Regional Park is an urban park located primarily in Buena Park, California south of Rosecrans Avenue at the southern edge of the West Coyote Hills. A smaller section with six softball fields is located north of Rosecrans Avenue in Fullerton, California. The park was originally opened as Los Coyotes Regional Park in 1981, and was renamed in 1987 after then-retiring Orange County Supervisor Ralph B.