This just an overview of rains of what appeared to be edible substances that have been processed. Except for the account at the end, it is a summary from Charles Ford's Book of the Damned.

Dried flakes, fibrous masses and other substances

In all cases, people had no idea what it was, and could only use comparisons in an effort to describe it. It does seem to be organic in nature, but dried and pressed into flat sheets or flakes. Well, somebody must have dried and pressed it before they released it into the atmosphere.

• A substance fell, that the people said they had never seen before. As to what it was, they had not a notion, but they saw that the sheep ate it. They ground it into flour and made bread, said to have been passable enough, though insipid.

• A substance fell, in lumps the size of a filbert, that had been ground into flour; that of this flour had been made bread, very attractive-looking, but flavorless.

• Flakes of a substance that looked like beef fell from the sky, "from a clear sky." It fell in flakes of various sizes; some two inches square, one, three or four inches square. It was a thick shower, on the ground, on trees, on fences, but it was narrowly localized: or upon a strip of land about 100 yards long and about 50 yards wide. Scientist found it to be composed of lung tissue, cartilage or muscular fibers.

• 1687: Thousands of flakes of a fibrous material that was pitch black in color fell near the town of Klaipeda (Memel) on the east coast of the Baltic Sea in Lithuania. Some of the flakes were recorded to be as large as tabletops and were all damp. To start with the flakes emitted a sour rotting odor that disappeared as the material dried out after which it could be torn like paper. Some of flakes were kept as curiosities and 150 years later the material was examined by the Royal Irish academy 1839 who stated that it was largely (Conferva Crispata) which is a form of threadlike green algae. No explanation was provided as to how this material had become compressed into flakes.

• A fall of flakes resembling coal-black, leafy mass. Some of these flake-like formations were as large as a table-top. "The mass was damp and smelt disagreeably, like rotten seaweed, but, when dried, the smell went off." "It tore fibrously, like paper."

• A fall of flakes, which looked like greenish felt.

• A fall of damp, coal-black, leafy mass. But, if broken up, the marsh-substance is flake-like, and it tears fibrously.

• In a triangular space included by these three towns. The substance is described as "cobwebs" but it fell in flake-formation, or in "flakes or rags about one inch broad and five or six inches long." Also these flakes were of a relatively heavy substance. "They fell with some velocity." The quantity was great: the shortest side of the triangular space is eight miles long. There were two falls of this substance at that location, some hours apart.

• A fall of "a mass of black leaves, having the appearance of burnt paper, but harder, and cohering, and brittle."

• A fall of a sheet of 200 square feet, of a substance similar to cotton-felt.

• A fall of a great quantity of a fibrous substance like blue silk.

• Several falls of silky substances.

• Numerous batches of spider-web-like substance fell in Montgomery, in strands and in occasional masses several inches long and several inches broad. According to the writer, it was not spiders' web, but something like asbestos; also that it was phosphorescent.

• A thick cloud, accompanied by rain and a violent wind, had appeared. This cloud was composed of a woolly substance in lumps the size of a fist, which fell to the ground. This substance
  that it was white, but was something that had been burned. It was fibrous.

• A brown dust that looked like vegetable matter.

• With snow fell a dark-colored substance, estimated at 500 tons, over a belt 50 miles by 10 miles. It was examined under a microscope, and found to consist mainly of vegetable matter.

• Several falls of dried leaves, large amount and for a while (10 minutes to half an hour)

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A Rain of Manna.

The sudden appearance upon the ground of a considerable supply of an edible substance astonished certain people of Asiatic Turkey one day last August. It came during a heavy fall of rain between Mardin and Diarbekir and covered a circular area some six or eight miles in circumference. Some of it was gathered up and made into bread, which was of good taste and very digestible. Specimens of the substance have since been submitted to botanists, who find that it is in form of small grains, yellow outside and white and mealy inside, and that it is a lichen known to occur in some of the arid regions of Western Asia. It is supposed that the grains were drawn up in a water spout and transported by the wind at it considerable height in the atmosphere. A French traveler has reported that a similar fall of this lichen did occurred in many parts of Persia in 1828, when it covered the ground to the depth of nearly an inch, and was eaten by animals and collected by the inhabitants. Many other falls are said to have been mentioned. (Trenton, (N. J.) American).

Source: The People's Journal (Pickens, South Carolina), March 12, 1891 page 4

[The amount of substance must have been large since people made bread out of it. They did not recognize it as lichens. If it was indeed composed of lichen, then it must have been processed first into the substance that came down. Also lichens are firmly attached to rocks and trees and do not cone off en masse. By the way, a water spout is over water, not over land.]