The farmers revolted because of high taxes they need to pay. These taxes led to poverty, the loss of their farms and imprisonment, causing them to revolt.
The highly profitable crop, well I think it was tobacco had a test on this so That's what I think, Hope this helped. :3
The Stamp Act of 1765 was an Act of the Parliament of Great Britain which imposed a direct tax on the British colonies in America and required that many printed materials in the colonies be produced on stamped paper produced in London, carrying an embossed revenue stamp.