The Power Seeds — D.B. Reynolds-Moreton

Alto didn't think of himself as a slave, but he was. Alto's clan served the priests in the city from their primitive village in the jungle, risking their lives to collect strange seed pods. Periodically, an emissary from the city would arrive, trade essential supplies for the mysterious pods, and then vanish into the jungle.
What purpose did these pods serve and why were they so important to the city dwellers?
Once the sinister truth about the pods was learned, Alto found himself bent on revolution and revenge. But a deeper truth was yet to be learnt.