Today, hundreds of thousands of pumpkin carvers will simply discard their pumpkin's seeds.
I believe tossing out pumpkin seeds is a terrible waste. Pumpkin seeds, roasted with salt and butter, are a delicious and nutritious snack. And they aren't difficult to make: separate out the pumpkin seeds, wash them well with water, dry on paper towels overnight, and then fry in butter (or toast in oven) until golden brown.
But to say "tossing out pumpkin seeds is wasteful" suggests that the person doing the tossing was, in some sense, making a mistake.
Now, it could be that people who throw away pumpkin seeds are simply ignorant - they do not know how to toast the seeds, nor do they know how delicious salted and freshly toasted pumpkin seeds taste. Lack of knowledge is preventing them from achieving a Pareto-efficient allocation of resources: