Tradescantias are persistent plants-easy to grow that sow their seeds widely.
They are so good at self sowing that once you have one in your garden you will always have them in subsequent years.
Scabiosa, originally known as "Sweet Scabious," was a plant that was first domesticated in herb gardens as a cure for the "scabious" which means itch.
In July Americans celebrate Independence Day and the French celebrate Bastille Day so it seems appropriate to think about red, white and blue flowers.