After doing a little research, I think this plant is Berberis darwinii or Darwin’s Barberry. This shrub is in a lot of yards around Boise. Apparently the berries are edible, but tart. Birds like them.
However, in New Zealand, this plant is considered an invasive species that is spreading quickly in forests and wreaking havoc with the native ecosystems.
What is harmonious in one place can be discordant in another.