>> , otherwise they would have no inherant value.
Anything rare has value. I guarantee that about 20 mins after the alien invasion, recipes for Tamanburgers would have appeared on the Interwebs. In real life, people eat/drink bird spit (swallow nests), fried insects, coffee that has first passed through a cat, cheese that has first passed through a maggot and the fluffy bits inside crocuses (which have sometimes cost more than gold, weight for weight)