Thalictrum thalictroides. Last year I saw a lot of Rue anemone leaves, but missed the flowers. Well, now I love the flowers. They're about 1/2" across, and they range in color from white to a luminous pink. They're also called Anemone thalictroides, if anyone asks.
False Rue anemone, which looks very similar, only comes in white, has a more deeply lobed leaf, and has tiny little tooth-like white things on the tips of the leaf lobes ("mucro").
These may not look like much at first glance, but they're pretty good viewed large (click on them).
Dutchman's breeches (Dicentra cucullaria) get me because their shape is so crazily atypical of what I think when I hear the word "flower". Who would think of such a thing! I would expect these kinds of antics from a tropical orchid, but not a spring woodland flower in the middle of Missouri. Give a kid a crayon and tell them to draw a flower and most of them wouldn't come up with something like this.
The top flower (above) isn't open all the way yet--
Very young flower stalks are all flushed pink like this
I must have taken a million pics of these. And next year I'll probably take a million more.
The leaves are pretty nice too