Leaves look like rudbeckia laciniata. One of the ugly ducklings of the otherwise stellar Rudbeckia genus (imo) This post was edited by dbarron on Tue, Sep 2, 14 at 16:56

If you visit the evening primrose about sundown you can watch the flowers open. Each flower opens for a single night, and the whole process takes only about 10 minutes. It is interesting to watch and kids love it.

It is a dayflower, probably Commelina diffusa (common in the Midwest). Run, screaming, from this flower...kill it now because if it seeds, you're going to have this thing all over your garden and forever. Ask me how I know...I've been trying to wipe it out of my vegetable garden for upwards of 10 years. Wrote about it in my book. Here is a link that might be useful: Garden Musings

The shiny yellow flower description makes me think of the Ranunculus genus: Buttercups. Pretty aggressive group if that's what it is. Here is a link that might be useful: creeping buttercup info