Pull or keep?

I found this tall plant growing out of the crack between the driveway asphalt and the brick of the house. My first thought was that is must be a weed to be growing there, but those flowers were so lovely, I thought they qualified for a blip anyway. I was curious though and asked my daughter for an opinion. She suggested that it could be a stray lunaria annua -  also known as Honesty, Silver Dollar or Money Plant. Who knew? Pas moi. I had only ever known the Silver Dollar plant by its seed pods; I had never noticed its flowers. Wish it had chosen a better place to take root though! Still don't know if I should pull it or let it flourish right there in the driveway!