When we speak of manna from heaven, we usually do so with a big helping of irony. In our time, the term has come to mean "something that's unheard of and unachievable."
As a seminary president, I sometimes sit with a donor and describe this or that new building or new faculty chair in the hope that the person will be moved to spectacular generosity. Occasionally I receive a skeptical question instead: "How do you expect to pay for this—with manna from heaven?" Manna from heaven, we think, is as likely to fall into our laps as pigs are likely to fly.
If we have misunderstood this text from Exodus, maybe we can be forgiven for it. Exodus is, after all, a catalogue of extraordinary things—the burning bush, the ten plagues, the crossing of the Red Sea, the Ten Commandments, the glory of God entering the tabernacle—it's as if the point of Exodus is to spoil us with evidence of the extraordinary ways in which God interacts with God's people.