One for sorrow
Two for mirth
Three for a wedding
Four for a birth
Five for silver
Six for gold
Seven for a secret
Never to be told
Eight for heaven
Nine for hell
Ten for the devil's very own self.

Counting rhyme, count the number of crows you see and this is what they represent.
Also said for Ravens, Blackbirds, and Magpies.
a group of crows is called a Murder, a group of ravens is called an Unkindness (as in, a group of sheep is a flock).

ive read several variations on this poem:
two for joy
three for girls
and four for boys
(no, the Counting Crows band did NOT make this up)
seven for a story thats never been told

and then, of course, theres Thirteen ways of looking at a blackbird