This "Pumpkin" is a crop that has been found by the Destiny expedition on an unnamed planet in a unnamed galaxy and in fact has a very pleasant taste, and is edible. After the expedition found the pumpkin, they cultivated them in their Destiny garden.
In 2010 when Destiny flew through a star so picking expedition as much of the plants in the garden and even some of the pumpkins. When the rest of the plants burned to the ground when the heat in the dome stage as soon. (SGU: "Blockade")