Ranunculus bulbosus isn't native to anywhere in the "new world" but is a European plant that has naturalized widely here.
The fact that the basal leaves aren't showing makes it harder to ID. Although the flower is a little out of focus, I'm seeing upturned sepals on the flower at the top of the photo, which would exclude Ranunculus bulbosus (which has down-turned sepals.) Ranunculus acris seems more likely, which is another European/Eurasian plant that has naturalized here. The flowers of acris and bulbosus do look very similar except for the sepals.
Actually, I think only the Houstonia, Sisyrinchium and possibly the Potentilla are native. Oh, and possibly the Myosotis if it is Myosotis laxa rather than the other introduced species.
