Deptford Pink [Dianthus armeria] photos were taken at Fletcher Park on 11 July 2013. It’s the member of the Pink (Caryophyllaceae) family. Newcomb’s Wildflower Guide, pages 258-259 states it blooms in summer and fall and can be found in fields and on roadsides. These were found just off one of the walking paths.
USDA Plants Listing: https://plants.usda.gov/home/plantProfile?symbol=DIAR