At an empty concrete lot in southwest China, Loulee Wilson scoops a handful of stones into a plastic bag -- a memento from the site where she believes she was abandoned as a baby. Wilson, an American college student, was born in China but given away by parents fearful of violating the country's "one-child" policy. Now 19, she is among a growing number of Chinese adoptees returning to their birth country to trace their biological parents and understand where they came from. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES