Exodus 16:13 And it came to pass, that at even the quails came up, and covered the camp: and in the morning the dew lay round about the host. - Free Bible Online

      13-31. at even the quails came up, and covered the camp--This bird is of the gallinaceous kind [that is, relating to the order of heavy-bodied, largely terrestrial birds], resembling the red partridge, but not larger than the turtledove. They are found in certain seasons in the places through which the Israelites passed, being migratory birds, and they were probably brought to the camp by "a wind from the Lord" as on another occasion (Nu 11:31).
      and in the morning . . . a small round thing . . . manna--There is a gum of the same name distilled in this desert region from the tamarisk, which is much prized by the natives, and preserved carefully by those who gather it. It is collected early in the morning, melts under the heat of the sun, and is congealed by the cold of night. In taste it is as sweet as honey, and has been supposed by distinguished travellers, from its whitish color, time, and place of its appearance, to be the manna on which the Israelites were fed: so that, according to the views of some, it was a production indigenous to the desert; according to others, there was a miracle, which consisted, however, only in the preternatural arrangements regarding its supply. But more recent and accurate examination has proved this gum of the tarfa-tree to be wanting in all the principal characteristics of the Scripture manna. It exudes only in small quantities, and not every year; it does not admit of being baked (Nu 11:8) or boiled (Ex 16:23). Though it may be exhaled by the heat and afterwards fall with the dew, it is a medicine, not food--it is well known to the natives of the desert, while the Israelites were strangers to theirs; and in taste as well as in the appearance of double quantity on Friday, none on Sabbath, and in not breeding worms, it is essentially different from the manna furnished to the Israelites.

JFB.