This is a wood anemone (European Anemone nemorosa), which would be a little scrub-wind-rose (Buschwindröschen), if you translate it literally from my language. While I'm nowadays very interested in the right taxanomy of flora and fauna,... I was rather creative as child. So this little flower was my "little dancing rose" (Tanzröschen), back then. I still see them dancing, now that I'm old. ;-)