I recently read that ambrosia, the food of the gods, is brought to Olympus by doves. But, who makes it? Is it natural to the earth (i.e. a plant)? Is there a deity that makes it and sends the doves to Olympus? What about nectar, the drink of the gods?
Amalthea, the divine goat who fostered Zeus until he grew up and could take revenge on his father Cronos, fed the god on her milk. In some stories this is called ambrosia; in other myths, she made ambrosia from her horns (which is where we get the modern image of the Horn of Plenty, or Cornucopia, used around harvest time).
(I can't find any primary sources citing the "ambrosia from horn" story, just repetitions of "other stories said," but I know I've seen it often.)
AMALTHEIA (Amaltheia). The nurse of the infant Zeus after his birth in Crete. The ancients themselves appear to have been as uncertain about the etymology of the name as about the real nature of Amaltheia. Hesychius derives it from the verb amaltheuein, to nourish or to enrich ; others from amalthaktos, i. c. firm or hard; and others again from amalê and theia, according to which it would signify the divine goat, or the tender goddess. The common derivation is from amelgein, to milk or suck. According to some traditions Amaltheia is the goat who suckled the infant Jove (Hygin. Poet. Astr. ii. 13; Arat. Phaen. 163; Callim. Hymn. in Jov. 49), and who was afterwards rewarded for this service by being placed among the stars. (Comp. Apollod. i. 1. § 6.) According to another set of traditions Amaltheia was a nymph, and daughter of Oceanus, Helios, Haemonius, or of the Cretan king Melisseus (Schol. ad Hom. II. xxi. 194; Eratosth. Catast. 13; Apollod. ii. 7. § 5; Lactant. Instit. i. 22; Hygin. l. c., and Fab. 139, where he calls the nymph Adamanteia),and is said to have fed Zeus with the milk of a goat. When this goat once broke off one of her horns, the nymph Amaltheia filled it with fresh herbs and fruit and gave it to Zeus, who transplaced it together with the goat among the stars. (Ovid, Fast. v. 115, &c.) According to other accounts Zeus himself broke off one of the horns of the goat Amaltheia, gave it to the daughters of Melisseus, and endowed it with such powers that whenever the possessor wished, it would instantaneously become filled with whatever might be desired. (Apollod. l. c.; Schol. ad Callim. l. c.)
I can't answer the part on who makes it, but what it could be, might help with the question. But I'll take a guess it's connected with Dionysus.
There is some who believe nectar and ambrosia are referred to interchangeably, with one being the drink the other the food or reversed. Stated here, the word nectar may have come from the Egyptian natron, which is a salt substance:
inserted through the nostrils and into the body as a way to preserve eternal life in the Egyptian tradition - John Lundwall - referencing R. Drew Griffith's book Mummy Wheat
Also, in Lundwall's article, he mentions Greek wine. At the time, they didn't have corks to preserve the wine. If it's opened, it needs to be drank or else it would spoil. A way to preserve it is by salting it, thus, prolonging it's life.
There's also an interesting insight into Greek wine itself and how that may have affected one's state of mind. The fermented drink perhaps was preceded by a barley drink as a kind of sacrament:
The notion that Eleusinian rites were celebrated with ergotized beer is entirely consistent with the notion that they had historical roots in Minoan Crete. In 1900 Sir Arthur Evans, excavating near the palace of Knossos, unearthed vessels adorned with ears of barley in relief. He therefore assumed that a kind of beer had preceded wine on Crete. Kerenyi believes that the small size of these vessels indicates they were used for a special kind of barley drink—-the visionary sacrament of the Eleusinian mysteries—in rites "allegedly performed without secrecy at Knossos." - Food of the Gods by Terance McKenna
In the same book, Greek wine is described as perhaps being more complex, could be a mixture of other plants, and thus produce kind of hallucinatory effects. The very title of the book seems to appropriate for the question here.
Wine played a central part in later Greek culture, so much so that in classical times the disturbing figure of ecstatic Dionysus was converted into the hairy-footed and lascivious wine-god Bacchus, the lord of orgy and, now, drunken revelry carried on in the traditional dominator style. The fermentation of grains and fruits must have been generally known and can claim no discoverer or point of origin. Greek wines have always been somewhat puzzling to scholars. Their alcohol content could not have exceeded 14 percent since, when a fermentation process reaches this concentration, further formation of alcohol is inhibited. Yet Greek wines are sometimes described as requiring many dilutions before they could be drunk with comfort. This seems to suggest that Greek wines were more akin to extracts and tinctures of other plant essences than they were to wine as we know it today. This would have made them more chemically complex and therefore more intoxicating. The practice of adding resin to wine in Greece to make retsina may well hark back to times when other plants, perhaps belladonna or Datura, also went into wine. -Food of the Gods by Terance McKenna
Ambrosia and nectar could have been the salt and the wine. You have the preserving qualities of the salt (immortality), with the divine ecstatic feeling you get from the wine itself (a possible hallucinogen, as it's not akin to the wine we have today).