The phrase pennies from heaven denotes unexpected benefits, especially financial ones.
The earliest instance that I have found is from The Fresno Bee (Fresno, California) of 12th January 1936:
The long-talked of Bing Crosby¹ picture to be made under the Emanuel Cohen² banner is being written by Jo Swerling from an idea which is described as “human and down-to-earth.”
Bing can not [sic] be spared from Paramount until April, so his first Columbia film will not be shot until the late Spring. The tentative title chosen is Pennies From Heaven, but neither Bing nor Manny Cohen likes it, so it is more than a guess that it will be changed.
(¹ Bing Crosby (Harry Lillis Crosby – 1903-77), American singer and actor — ² Emanuel ‘Manny’ Cohen (1892-1977), American film producer)
It was under that title, however, that the film, a musical comedy, was released in the USA on 25th November 1936. And it was in that film that Bing Crosby introduced the song of the same name (words by Johnny Burke (1908-64), music by Arthur Johnston (1898-1954)); the following is from the Catalog [sic] of Copyright Entries (1936):
Pennies from heaven: from Pennies from heaven, w Johnny Burke, melody Arthur Johnston. © 1 c. May 1, 1936; E unp. 123687; Select music publications, inc., New York. 14575
(© 1 c. stands for: copyright registration of an unpublished work; it is followed by the date of receipt in the Copyright Office of the printed or manuscript copy; E stands for: Musical compositions.)
The phrase, therefore, predated both the film and the song; the second-earliest instance that I have found is from the Chula Vista Star (Chula Vista, California) of 26th March 1936:
Pennies From Heaven
No news is better news than a rate cut in some basic necessity of life. Out of your budget comes money you’d thought as good as spent. It’s like manna from the skies, or, in more modern terminology, like pennies from heaven.
Thus commuters across San Francisco bay are wearing broader smiles these days. Sharp slashes in bridge tolls and ferry fares, the latest of which came less than a fortnight ago, have cut the cost for an auto and four passengers across the Golden Gate or the bay to 50 cents. Some say this is one reason why bay area inhabitants should find it desirable to keep the auto ferries for a good many years. Should the body in charge of the bridge get a yen to pay off bridge costs in five years instead of 20, and therefore boost tolls, the ferries will always be there as a double check. Anyway, there may be more of these “pennies from heaven” for bay travelers. Congratulations. It’s good to see people happy, and getting some breaks for a change.
Abraham Burstein (1893-1966), American rabbi and author, had used a similar phrase in The Ghetto Messenger (Bloch Publishing Company – New York, 1928); Abie, an elderly man employed at the telegraph office, writes fictitious telegrams in order to solve problems in the neighbourhood; he is delivering one of those telegrams to a boy named Charlie:
“Let me read it for you,” cried Abie. “Listen:
“‘Heaven, Thursday. God is pleased with your reading and will reward you many times if you learn well. . . .Angel Gabriel.’”
Immediately a clamor arose from all the children. “It ain’t so!” “Is it really from Heaven?” “Let us look at it, Charlie!”
But Abie was equal to the occasion.
“Didn’t you hear about God writing everything down that you do here? Well, electricity comes through the air and carries messages even from Heaven, ’way up in the sky. Here, you can see the telegram for yourselves.”
The boys looked doubtful, but then, on actually seeing the yellow message, similar in every respect to others they had remembered glimpsing in their homes, they began to look soberly upon Charlie as a favored of the Lord.
Charlie showed his telegram to his father. That gentleman, being cognizant of “pennies falling from heaven” and other tricks of clever m’lamdim [= teachers], appeared to take it seriously, but later laughingly related the incident to his wife.