The Seacook by Robert Lewis Stevenson.

Treasure Island by Robert Louis Stevenson was first published in 1883, and is an adventure novel narrating a tale of "buccaneers and buried gold". Traditionally considered a coming-of-age story, Treasure Island is a tale noted for its atmosphere, characters and action, and also as a wry commentary on the ambiguity of morality -- unusual for children's literature.

The influence of Treasure Island on popular perceptions of pirates is enormous, including such elements as treasure maps marked with an "X", schooners, the Black Spot, tropical islands, and one-legged seamen bearing parrots on their shoulders. (From Wikipedia).