David, do you remember what the seed was like? In the last few years, we have several times had donations to the AGS seed exchange labelled Pulsatilla occidentalis (or Anemone occidentalis) which have been fluffy cotton wool seed, and not typical feathery seed, which is what P occidentalis should have.
The real thing is a beautiful species but sadly, extremely difficult to grow. I've tried several times but not got it through the winter. Graham Nicholls has had some success with it and told me the important thing is to keep it dry in the winter and not water at all until you see the new growth in the spring.
