NEVADA COUNTY FAIRGROUNDS. The 50th annual Father’s Day Bluegrass Festival — the landmark golden anniversary of this family-friendly celebration of bluegrass music. The four-day event, staged by the California Bluegrass Association, features over 30 national, regional and local acts, workshops, jamming, square dancing and youth activities, all taking place under the towering pines of the beautiful Sierra Nevada foothills. Fri-Sat, 9a—11p & Sun, 9a—5:30p. $35—275