The Forgotten Garden by Kate Morton

In 1913, a four year old girl is abandoned on a wharf in Australia. Unable to remember her name or how she got there, she is taken in by the dock keeper and his wife and raised as their daughter. At the age of twenty-one, her odd beginnings are revealed. Shocked at the truth, with a vague memory of someone called the Authoress, she withdraws from her "pretend" life. In 1975 Nell, as she is known, receives information that leads her to a cottage with a marvelous garden on the Cornish coast of England. A child's suitcase and a rare book of fairy tales may hold the key to her identity. Life intervenes and it isn't until 2005 that her grand-daughter returns to England to continue the search. The reader travels back and forth in time, learning the story backwards and forwards. The sprinkling of Victorian romance and strong-minded characters makes this a satisfying mystery.