Soapweed yucca is native to central and eastern Montana (east of the Divide, basically), but it's such a great plant for xeriscape and low water landscaping that I've included it in the lineup.
 
The stiff sword-like leaves grow from a central point, reaching up to two feet. Mature yucca produce a tall stalk up to four feet tall whose numerous white-ish bell-shaped flowers are pollinated by moths and butterflies. Additionally, this is a critically important plant from an ethnobotanical perspective; its various parts have been used medicinally, to produce soap, and to produce fibers, among other things.
 
You too could have a yucca, assuming you have location that gets full sun and drains well. Yucca are highly drought tolerant and happy growing in poor soils. However they won't put up with shenanigans like sprinkler overspray. They are also deer-resistant (I've had deer chew on them, but they don't make much progress. YMMV).
 
Yucca will grow well with pretty much any of our low water plants. Consider tufted evening primrose, fringed sage, hairy golden aster, rubber rabbitbrush, and wyeth buckwheat. 
 
 
image credit: 
Matt Lavin from Bozeman, Montana, USA, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
Kenraiz, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons