Many years ago a young Crow mistakenly feasted on a succulent Pumpkin, and then fled when the sapient Plant attacked him.
The wound was not particularly harmful but left the Pumpkin scarred and bitter. The bitterness became madness over the years as the Pumpkin plotted revenge on all Crows.
The Pumpkin turned to Gourmancy, and after years of experiments, he at last had the means for revenge. In that time, the Crow family moved on and a family of Blackbirds has come. Unfortunately, the Mad Pumpkin makes no distinctions.