It looks a bit like a mallow to me -- not the common or marshmallow types with their rounded leaves but more like the musk mallow or mallow moshata. The flowers appear to be white though (or very pale pink) which is not characteristic of those species. Still, based on the interior appearance of the flower and that leaf pattern, I think a closer look at some of the mallows may be in order. At least until I come up with a better idea.
