In Swedish, we call this flower midsommarblomster (= Midsummer flower).
The Latin name is Geranium sylvaticum. In England it is called Wood Cranesbill and is the county flower of Sheffield; and in North America it goes by the name of Woodland Geranium.
Depending on soil conditions, the flowers range from a mauve color to sky blue. It can also be found with white flowers. From the flower a blue-gray dye can be produced, which was used in the past to dye war cloaks (according to Wikipedia).
I came across these on my way to the Midsummer celebration; and again it was one of those occasions when the name just popped up in my memory from I-don’t-know-where-or-when.