Does look like crape myrtle but crape myrtle is not native to the United States.

Thanks so much, Carol! I thought I knew it all, then someone gave this as gift and I was amazed I'd not seen it before, and yes, it is lightly fragrant.

Catharanthus roseus... Madagascar periwinkle... a variety of colours... a bit of a weed in some areas https://en.wikipedia.org/wiki/Catharanthus_roseus

Windberry, you misunderstood me. Maybe I didn't make myself clear. Although I said 'as if they were hardy native plants' I did not say only native plants could be naturalised. I said 'suitable plants'. Not the same thing at all. Of course the OPs plant isn't an exhibition variety. No one said it was but neither is it a tough original species. It's a refined hybrid. I am well aware of what 'naturalising' means both in ecological and horticultural terms. In my view Chrysanthemums of whatever type, are not 'suitable plants' for wild gardening, which is a far more complex activity than simply leaving a bunch of plants to fight it out. That is neglect rather than gardening. There is a reason Chrysanthemums are not seen dotting our roadsides. They simply can't survive outside a setting in which they are protected from competition. While the flowers of the OP's specimen are pretty enough, the blooms could be more prolific and the plant could be larger and healthier without the competition. I would be prepared to bet that if not given some care it will dwindle to nothing in a year or two. Anyhow, Abid hasn't returned to tell us what style of gardening he prefers, so we don't know whether he is looking to grow this plant as well as possible or simply wants a pretty spot of pink in the yard for a couple of seasons.