Deptford Pink

From the Great River and Clarence Cannon National Wildlife Refuges:

Deptford Pink flowers can be found in fields, pastures, prairies, waste places, and roadsides. A native of Europe, it was probably first introduced to North America as a garden ornamental, although today it is rarely cultivated. People have moved plants around the world, sometimes on purpose and sometimes on accident. In some cases, these introduced plants "escape" and can become classified as "naturalized," which means they grow and reproduce on their own, out of cultivation. Not all naturalized plants are invasive.