These are rue anemones. Thalictrum thalictroides.
Notice the leaves. Notice that there are more than five petals. Notice that there are a bunch of flowers on one plant.
This is often confused with wood anemone, which only has a single flower on a plant, and canada anemone, which has sharply pointed leaves.
Rue anemones are also often confused with this wildflower. This is false rue anemone. Enemion biternatum.
It always has five petals.
This is bloodroot. Sanguinaria canadensis. You guessed it, when the roots are cut, they exude a red sap. The leaves are lobed like a fig leaf and sort of a gray-ish green. The leaf comes up wrapping around the flower stem.
I love these. Often you'll see just the flowers and the leaves will come up after the flower has died back. In springs where the weather warms of very fast, like this year, the leaves pop up as soon as the flower opens.
This is hepatica. Anemone acutiloba. Also called liverleaf because the leaves are liver-shaped.
These bloom white, pink and purple. The flowers come up before the leaves. It loves the rocks around here - shallow dirt pockets in tree roots and crevices. These often bloom before the others, in March as soon as the days warm up and the snow stops. This year everything is blooming together.