Family: Sunflower (Asteraceae)
Habitat: These flowers tend to show up in meadows and along streambeds. The meadows along Glacier Point Road are a good place to look. Most years you can find them (the flowers, not the meadows) in Summit Meadow near the road.
Flowering Season: June - September
Origins: Native (see distribution maps for California and US/Canada)
Size: Plant 1 - 3 feet high, Flowers 2 - 3 inches across. It's easily spotted in the wild.
Helenium bigelovii etymology: The Helenium genus is named for Helen of Troy. Bigelovii has nothing to do with HBO or polygamy; it actually honors American botanist John Milton Bigelow (1804 - 1878).
This Photo: In Summit Meadow, mid July. (Summit Meadow is next to Glacier Point Road, about a mile west of the McGurk Meadow trailhead. There's a parking pullout and an outhouse here; you can't miss it.)
Other Resources: CalFlora · CalPhotos · USDA · eFloras.org