Insects. Intellectually I know they are edible and a good source of protein, but personally I don’t consider them to be food. Yet I can happily eat their relatives, shrimp, lobster and crab. Go figure.
Dandelions are definitely edible. We used to eat dandelion greens when I was a kid, and there is, of course, the literary reference to dandelion wine as well as the actual stuff.
There is also pine needle tea, which I used to make and consume when backpacking in the Sierra Nevadas. It’s a good source of Vitamins C and A.
Nasturtiums, roses, violets and other edible flowers have long been consumed by people and are currently making a big comeback in fancy restaurants. However, you need to be 100% certain that no pesticides have ever been used on them.
I have also consumed a variety of reptiles and a few amphibians that don’t usually show up on supermarket shelves. A lot of them do tend to taste like chicken.
If you want to see a whole bunch of strange foods, try checking out this site. Also watch for Andrew Zimmern’s show Bizarre Foods.
And then there is the Durian