I’ve got a bunch of these that popped up in my garden bed. They’re really lovely, but I know I didn’t plant them! Any ID assistance would be greatly appreciated.
The blossom looks a lot like something in the hibiscus or althaea families (rose of sharon, (marsh)mallow, hollyhock, Althaea, etc.), but the leaves are far too narrow and lobed for anything I’ve seen in those groups. You might kick around Google™ Images using those names as keywords to see if any cousin turns up matching your plant.
Althaea Cannabina has lobed leaves, although not exactly like yours.
(Don’t be misled by the colors: they all come in a wide variety of whites, pinks, and purples with a lot of variation, even on the same plant.)
BTW, I used “families” in a very non-technical (i.e. wrong) way in the last post. the Family is Malvaceae of which the hibiscus and althaea each provide a prominent Genus (with some plants being moved back and forth between the two as horticulturists wrangle over where they belong).
A geographic location (“Midwest”, “Northeast”, “Borneo”) would be helpful. 
ETA: It’s not a hollyhock, because they’re biennials and the first year put up only a rosette of leaves, then they bloom the second year, on a 5-foot high stalk.
Careful, Hibiscus trionum is listed as a noxious weed in some states. It is one you probably don’t want to cultivate, as it self seeds and can get pretty annoying.
Thanks for the quick replies! I will be sure to get it all pulled up and thrown away before it goes to see. Too bad is a noxious weed - it’s really pretty!