I have already voted on the matter of domesticated fruits, but around here, we also have some wild fruits that are quite delicious and that I always sought out as a kid (I grew up out in the boondocks, and it had its advantages).
Most famous perhaps is the marula (
http://en.wikipedia.org/wiki/Marula), but you don't find them in this particular part of Gauteng because the winters are too cold. They are not really my favourites anyway, though the fruit is often used for jams and liqueurs and things.
On small farm where I grew up, there were some wild apricot bushes. The fruits superficially resemble apricots:
But they are really unlike any domestic fruits. They usually contain several large seeds with a thin layer of fibrous pulp around them, and you don't eat them so much as just suck them like sweets. When completely ripe they are delicious, with an exotic taste unlike anything else, though after a minute or two the taste suddenly goes very sour, and then you spit out the seed to create the next generation of shrubs. Also, you have to be quick in harvesting, or the baboons will get there before you.
Well, what do you know, there is actually a Wiki page:
http://en.wikipedia.org/wiki/Ancylobothrys_capensis