Anemone Smut (Urocystis anemones) affects various members of the anemone family especially Wood Anemone (Anemone nemorosa), causing blister like swellings beneath the epidermis which rupture to produce dark brown spore-balls.  The spore balls consist of 1 or more brown spores, surrounded by some hyaline sterile cells.

host

Photograph the smut and the host; note the host-plant in your comments.  Ensure your photo shows the dark spore-mass.

on Wood Anemone; in woodlands

Scarce; very few records known