Viola missouriensis most likely.

funny violet story ..

in suburbia.. i was a lawn warrior ... grass was king .. the gardens just to show off the perfect lush lawn ...

my usual way to clean refuse out of the garden.. was to just fling it over my shoulder.. out into the lawn .. dog thought it was a great game .. and then.. at the end of the day.. climb on the lawn tractor.. and just pulverize it all into the lawn ... free lawn food ...

got very p.o.'d at violets one day ... and went after them with a vengeance.... flinging them into the lawn ...

for the next 2 years.. i was killing violets in the lawn.. got a real hate on them ... they were bad enough in the garden bed .. but crikey.. stay off my lawn ... and i wasnt even a cranky old man back then .. lol ...

fast forward to 5 acres of sand that was former horse pasture ... in MI.. with summer heat.. and sand ... anything called a lawn out here goes dormant in early july ... well most anything .. lol ... the only thing green in my mowed areas .. i hesitate to call it a lawn .. was violets ... lol.. and other meadow WEEDS .. some of you would probably call them natives ...

so... over time.. i came back to loving violets.. because they gave the appearance of a green mown lawn in the heat of summer ...

ken