Most pumpkins and squashes are edible. If you got yours in the fruit and vegetable section of a grocery store, you should be fine. Pumpkins for carving (often large or mini), are edible too. Smaller pumpkins usually have a sweeter flavour. Larger pumpkins tend to taste a bit bland. Ornamental pumpkins (gourds) are often edible too but have no taste. You will recognise gourds by their look - they are often curved and colourful. Remove their though skin prior to cooking them. You may be better off using them for decoration only (they normally last long). If in doubt and your pumpkin tastes bitter, it is safer to throw it away.