If you stop and think about it, how did we get the idea to eat eggs? “Hey, you know those things that come out of the chicken’s butt? I’m going to try eating one of them. Who’s with me?”
One must also wonder who first decided that certain types of fungus were edible (especially truffles).
Popcorn may have been first discovered by accident, as some of the above posts suggest. You don’t really need a special variety of corn for that. Other kinds will pop too, once they are dried out. They don’t pop very well though – too much hull.
I once tried popping some kernels of Indian Corn. A few of them popped, sort of. I suppose once that is discovered, then it’s just a matter of developing a particular breed that pops well.
According to a certain comic book I read as a child, Superman traveled back in time to the Roman era once for whatever reason. (I don’t remember any details.) There, he found he needed some Roman money for some reason. So he found a field of corn, popped it with Heat Vision, and hawked it among the Circus spectators at the Colosseum. Those consumers, having never seen popcorn before, raved over it and declared it a food for the gods.
<portal>The first person to discover that cow’s milk was drinkable was very, very thirsty.</portal>
Animals eat eggs all the time. I doubt it was learned, just inherited from the countless generations of hominid ancestors who have always eaten eggs. If it was learned, it was a pretty simple “huh, animals eat eggs. I guess those things are edible.”
Almost all animals and animal parts are edible. The first person to try eating animal x is probably the first person who came across that animal and was able to kill it. People gotta eat, after all.
Animals like puffer fish that are actually toxic are quite rare.
Neat trick. But Superman would have first had to have imported maize, which was unknown in the Roman Empire (or the entirety of Europe) before the 15th Century CE. :smack:
Comics books. Terrible way to learn history. 
Well, to be blunt, Silver Age Superman would have had no trouble at all flying to Yucatan or wherever and “borrowing” all the popcorn he could handle.
Which would have been a neat historical fact to include…
Most human adults are what we in the layperson community call “lactose intolerant”: They can consume dairy, they’ll just wish they hadn’t.
Me and my relatives and ancestors are an exception. I’m capable of eating as much dairy as I can cram in without so much as a twinge later on. Us light-complected round-eyes got the good end of the mozzarella stick, as far as I’m concerned.
The dominant theory for how this happened is that lifetime lactose tolerance was bred into us due to our ancestors needing milk to survive; those who could suffer through the ass-termath marginally better than their cohort got to make more children, who then had an advantage the next time milk came before (or instead of) meat.
So here we have the historical tableau, an untold number of generations unknown doubled-over and fertilizing, each a bit less urgently than the previous, and at the end their doughty descendents could dabble in the domestic delicacy known as the fried cheese curd. Little could stem their tide, but now we can make our own whey!
Alternatively, “Hey, that fragile rock thingy becomes a chicken if you leave it for long enough. If I eat it now, it’ll be as if I’ve eaten a whole bird and I won’t go hungry for days!”
Time passes
“Aww…”