Nonea pulla, or in english simply nonea, or monkswort. From my native language, her name can be literally translated to english as nun-flower.
The dark purple color of the flowers sometimes seen as almost black. Found it quite hard to photograph, due to the unexpectedly huge contrast between the green-greyish leaves and the deep dark purple petals. (and the fact, that my dog had to lie on my back while I was crawling in the grass taking the picture. )
(05.11)