Unnamed spotting

Yup, my guess would be Oregon Grape. Pretty sure..

Chiara, I'm curious as to how you're differentiating this from Mahonia repens from this picture.

So, according to the PLANTS database only repens (creeping) and aquifolium occur in Montana, while the Montana Plant Life website seems to think only repens does. If this one is low and, well, creeping, it'll be Mahonia repens, if its more upright and shrub-like, it'll be Mahonia aquifolium.

Oregon grape. I would guess Mahonia nervosa, but could be Mahonia aquifolium, or maybe Mahonia repens, hard to tell without being able to see the growth characteristic.