Answer: I'm guessing Campanula (which might be too obvious) or Adenophora confusa, also called 'Lady Bells'. If the flowers are in clusters, it might be Mertensia virginica (Virginia Bluebells). If none of these are right, there's a book entitled "Taylor's Guide to Perennials", ISBN# 0-395-40448-7, which might be of help to you. The book divides perennials into flower color as well as bloom time. It's loaded with pictures and plant descriptions and may feature the plant in question. Good luck in your search!
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