Virginia spiderwort (tradescantia). Looks like a grass or weed, and some people think it is because it has a habit of popping up all over the place. Each stem bears only one purple/blue flower but has a cluster of buds that will open one at a time for several weeks. Behind that is a clump of purple-leaf loosestrife. As spring progresses, that will grow two to three feet tall and the color will change to a purple/green blend. In late summer there will be one very small yellow flower at the tip of each stalk. I usually end up knocking it back when it gets so tall that is flops over but that doesn’t seem to discourage it at all–in fact, like most plants, I think it enjoys the occasional haircut.