The early Celts had a battle goddess who appeared as a crow, a sign of death and destruction. Yet in a modern superstition, finding a dead crow in the road portends good luck. The frightful raven that haunted Edgar Allan Poe was a member of the crow family, but the Aboriginal people of Australia thought of the crow as a clever trickster, who first brought fire to humankind. Crows are thought of as ill-omens, but they can foretell good luck as well.
There is a crow rhyme that is supposed to predict the future. It comes from Europe and probably refers to groups of magpies, a crow relative. It goes: "One crow sadness, two crows joy, three crows a wedding, four crows, a boy." Not bad, so far. In one version though, the rhyme goes on: "Five for silver, six for gold, seven for a secret, not to be told. Eight for a wish, nine for a kiss, ten for a state of heavenly bliss." On the whole, these crows predict good things. Of course, there are many ways to count crows, some less optimistic.
Here's another cheerful one, "Two crows I see, good luck for me." That saying is from Wales, where they also believe one crow crossing someone's path to be a dire omen, in much the same way others feel about black cats.
A gathering of crows is techincally called a flock, but many have taken to calling these groups 'a muder of crows' when they desire to wax poetical.
Badbh Catha means "Battle Crow" in Old Irish. It's the name of an Irish war goddess, who, along with the goddess Morrigan, could change at will from a black bird to a bent old woman dressed in ragged black. The appearance of these goddesses, or their supposed appearance, presaged defeat for soldiers who saw them. The Badbh Catha in particular would appear on the battleground after the fight was over and gloat over the bodies of the dead.
Black crow flying
Joni Mitchell wrote a song called 'Black Crow Flying.' For her, perhaps crows is as much about perception as dread.
The group Counting Crows has a spooky crow-counting song, 'A Murder of One,' on their album August and Everything After.
'The Twa Corbies' is an old Scottish song whose writer imagined two crows chatting as they sat over a fallen knight. The song makes effective use of the traditional link between crows and death.
Crows call to each other in harsh piercing shrieks that can be startling to someone who has not noticed crows nearby. Worst of all, crows eat carrio or dead flesh. These are the real reasons that crows are considered ill-omened. In fact many societies have considered crows messengers form the underworld, destined to bring plague and pestilence, or bloody war.
About real crows
Actually, crows have many useful, non-death related skills. The New Caledonian crow can make useful tools out of leaves and grass blades. Other crows have figured out how to drop hard nuts on the street so that passing cars will crush them open. Crows are truly intelligent--much too smart to have superstitions about humans.