Aqueligia, or Granny's bonnets.
I spend a lot of my professional life pulling out weeds. But when is a plant a weed? This Aqueligia certainly wasn't sown by me, but at this time of the year, in this border, it's a lovely addition. When it strays over the drive to my foliage border, then it's a weed, and i've been evicting them before they overtake my Hostas, but here i'm quite happy to let them stay, - under control. For flower between the tulips and the summer perennials.