These Asiatic Dayflowers reminded me of my Brooklyn childhood garden (see below for Google Maps image of the house today) because they were about the only thing growing in its barrenness, until I planted some privet hedge cuttings I had rooted.
In Brooklyn the plants were very small, obviously lacking nutrition. (Perhaps I've misidentified plants I saw when I was 10 years old! They may have been spiderworts.)
Here in Western North Carolina they are humongous and only arrived THIS YEAR in a load of mulch.
They're not bad to look at and I'm hoping they will crowd out the ugly Japanese stilt grass.