I have always been fascinated by the fact that a group of crows is a murder. Who first decided that this was the correct name for a collection of the carrion birds? I don't know, but their imagination was so spot on.
We know--and expect--certain collective nouns. A herd of horses, a school of fish, a pride of lions. But you can really spice up your writing with some of the more unusual ones. It is always easiest to find the animal congregations. A good list can be found here. But animals aren't the only groups of nouns. There are also names for groups of people and things. Some of those more uncommon nouns can be found here.
Let's have some fun. Can you match the group to their collective noun -- without looking?
or what about these?
But not all group nouns have been given names yet, and you can have a lot of fun with those. For example, in one of my short stories, I had a group of cheerleaders, and I wanted to refer to them with a collective noun. They became a "giggle of cheerleaders." I was extremely proud of that one. ;)
Remember, a little goes a long way--especially with some of the more esoteric combinations, such as an "implausibility of gnus." This is a spice to use sparingly, but it can really add something to the mix.
(I will give you the answers next time. ;) )