[Taxacom] NE USA herbaceous plant ID request

[John Grehan]

If I can be forgiven for making a trivial identification request, and
hoping that there may be a botanist familiar with herbaceous plants in the
northeastern US, I am curious about the identity of a herb growing at my
home for which I have not been able to find anything comparable on the web.
As I am not native to N America, most herbs are a bit of a mystery to me
and don't have any other ready options.  The plant has the following
features:

About 30 cm in height
Appears to be an annual (it turned up at the base of a tree two years ago,
disappeared last year, but growing again under the same tree but in a
different spot).
Flowering now (starting about a week ago in June)
Leaves each with a long petiole and in the form of about 4 main branches
where the leaf area is reduced to a narrow rim along each main vein and 4-5
secondary veins along each main vein (so it looks like a bunch of fingers
each with subfingers).
Flower is a pale lavender color, actinomorphic
5 short, wide, green sepals, each narrowing to a point
Each sepal subtended by shorter and narrower sub-sepal
5 petals (petal length about 20 mm)
Distal margin of each petal forming a very shallow V from each corner to
the center
Reproductive organs on a short 'stem', not quite sure what is what, a mass
of short, soft tendrils for the lack of a better word, some ending in
slightly enlarged blade like structures, rest lined with pale round
objects. Sorry for the vagueness. If anyone was interested and in need for
determination I could send a photo.

Many thanks,

John Grehan