Forklore: How sweet it is
Manna isn't just a miraculous food that saved the Children of Israel during the Exodus. There are a number of mannas in the modern world, all being sweet things that appear mysteriously. One is Lecanora esculenta, a sweet lichen that grows in the deserts of the Near East.
Most mannas are droplets of sugar that appear on plants infested by scale insects. The classic Near Eastern manna shows up as honey-like droplets on tamarisk bushes; scientists are not sure whether the manna is produced by the insects or whether it's just a form of sap that exudes where the insects puncture the plant.
This kind of manna comes mostly from Kurdistan. The Kurds gather the droplets from the tamarisk plants, add them to boiling water and then clarify the manna with eggs to remove impurities before selling it. It's either eaten as is or put into pastries.
Many other plants attacked by small insects exude manna -- even some grasses. A manna gathered from European ash trees contains a certain sugar named mannitol, which is used in baby laxatives. How sweet.