I din't really notice this lovely sunflower until I moved up to the Mission Valley. At the peak of summer and heading into fall, Nuttall's sunflowers glow along creeks, irrigation ditches, and swales. Drive to the Bison Range in July, and you'll see it growing thick along Mission Creek. It's very similar to maximillian sunflower, but much more prevalent in our area (maximilian could be considered an eastern MT equivalent).
 
This rhizomatous perennial blooms prolifically on tall, sturdy stems. The flowers are yellow and about two inches across. The seeds are held in the dried flower heads, and as winter approaches they provide a significant source of food for migrating and overwintering birds alike. 
 
Nuttall's sunflower likes full sun and moist soil, although they can tolerate periodic drought. They are TALL, and they spread, so keep that in mind when picking a spot. They are perfect for areas you are hoping to naturalize, but might not work out so well in small confined gardens (unless you are going for a nuttall's sunflower garden). 
 
Last photo credit:s
Matt Lavin from Bozeman, Montana, USA, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons