Last year I noticed a little circle of them, and this year there are tons more. They're probably some horrible invasive, but I kind of like it. It doesn't grow more than 8 inches tall, which is perfect for my "meadow" and it doesn't have seed heads, and stays dark green even when everything else has gone a dormant yellow. But I'd like to know what I'm getting into before I let it go wild in my yard.

This is it without mowing

This is after mowing