Sister #1 has corrected me. She has a Masters in horticulture. She is also a Master Gardener. She knows a lot more about green things than I do. She told me the flowers in the photo I took are not phlox. She says they look a like wildflower called Dames Rocket, which is considered an invasive weed. She said phlox has five flower petals, not four, and phlox blooms much later in the summer.
However, she really likes the invasive weed variety and she has some in her home garden. She also said she'll give me some. :^) I shouldn't have any problem growing them.
Now, if I do write a scene with those flowers in them, I'll be able to give them the correct name.