Are there naturally occurring foods that are blue? Not foods that have been created in a lab to be blue?
A few that came immediately to mind:
- Purple potatoes (sort of blue-violet)
- Blue corn (readily found in the form of corn chips)
- Lobsters are blueish (until cooked when they turn bright red, so nobody thinks of them as blue)
- Some edible flowers
An excellent answer can be found at Skeptics.SE, complete with lots of pictures.
Even if limited to foods edible to humans, a few others do come to mind, each of which occasion in true blue hues (though not necessarily always).
1.the Concord grape
2.the juniper berry (used for making gin)
3.varieties of cabbage, squash, and mushroom (from which the band Blue Oyster Cult apparently derived its name)