I had planted a mesclun mix there last fall. Anything that survived the winter had bolted. I believe it is the endive that bolted. Endive is in the same genus as chicory, the roots of which can be used as a coffee substitute.
Since my son always recommends "a touch of blue" in the landscape, I suggested he go take a picture. On his way out, he took a picture. As he walked by the window, he shouted that it was PURPLE not blue! Later, (sometime in the afternoon), I went by to take a picture, but the flowers had shriveled in the heat of the day. I went out this morning to shoot pics while the flowers were still fresh. I think the newer flowers are more bluish and the older flowers take on a more lavender color.
This is the first time that I know of that I've had any chicory of any kind blooming on my property. It is so pretty!