Snowdrop Anemone, Windflower (Anemone sylvestris), fam. Ranunculaceae.
As seen from the photos, it is found in a garden bed – and not in the forest, as could be supposed from its name. It blooms in the middle of spring. Provides antiseptic, analgetic action; however, anemone is also very toxic, like most plants in the Buttercup (Ranunculaceae) family.