I'm sure this was posted recently from another location, but I can't find it. These are plentiful at Fort Worden State Park in Port Townsend, WA, along Harbor Defense Way, the road to the lighthouse. Maybe the stems are red, not purple. I didn't measure the flowers, but I think they were around 5cm across.
Grindelia, I lean toward Grindelia integrifolia from what I can see of the leaves (other possibility is Grindelia hirsutula)
Thank you, @Daniel Mosquin. I am attaching a photo that shows the leaves. There are not the serrations along the edges shown in the Wikipedia article for Grindelia integrifolia, but it's not really hairy, which "hirsutala" would imply. I see in the BPotD Grindelia integrifolia article a comment by Ed Alverson, January 6, 2009 at 10:59 am, saying "The plant that Flora of the Pacific Northwest calls G. integrifolia var. macrophylla is generally a maritime species, occurring on shores, salt marshes, and coastal bluffs. At the species level it is called G. stricta." But the Wikipedia photo caption says "Note that Grindelia taxonomy is historically a big, fat mess and it's almost safer to follow this species by it's venacular name, Puget Sound Gumweed. E-flora BC calls this Grindelia stricta but that is an artifact of the pre-molecular taxonomy system they follow."
Zooming in on that last photo, there are plenty of hairs. But the leaf photo of G. hirsutala at E-Flora BC Photo Gallery: Photo Details shows quite different leaves.
