I can' think of any events that "shaped" his dream. He did negotiate with Britain over the Oregon border and tried to buy California from the Mexican government before the Mexican War. Maybe that's what the question asks for. Try this site in addition to the one I gave you before:
http://www.whitehouse.gov/1600/presidents/jamespolk
Were there any key events in James K polks life that shaped his dream for the United States?
I can't find a source that seems to fit this question.
3 answers
Actually, Polk is famous for having clearly stated goals or "dreams" when he took office, accomplishing them, and going home!
i don't think that is what callie was looking for she is looking for what shaped his dreams