In Indiana's sand country, flowering spurge often grows in the most barren areas and blooms freely in the midsummer sun. The flowers are small and delicate, and the plant has a milky white sap that helps prevent dessication. While this plant is considered a weed farther west, it seems benign enough in the eastern portion of its range where, probably because it can only compete in the most xeric of circumstances.
Many authorities state that the milky sap is an irritant if contacted by the skin; I've never experienced this but it may require a considerable dose to have an effect. However, there is general agreement that his plant can have powerful toxic effects if ingested; I'd recommend looking at it and leaving it alone.