In American English, collective nouns are nearly always treated as singular. They emphasize the group as a unit. Occasionally, when there is some reason to draw attention to the individual members of the group, a collective noun may be treated as plural.
Singular: The class respects the teacher.
Plural: The class are debating among themselves.

Rules for Writers, Fourth Edition, Diana Hacker, Bedford-St. Martins, 2000

Ah, but sound must play a role; mustn't it? The problem began buzzing in my head while reading a novel, The City of Dreaming Books by Walter Moers, translated from the German by John Brownjohn. The sentence reads: And rocks were all there was; nothing – not a single living creature; not even a plant – obtruded its presence on the pure geology.

My sense of right and wrong, correct and incorrect usage, began shrilling its alarm. Shouldn't that read “rocks were all there were...”? Say it out loud. Rocks was. Rocks were. It must be the latter. It simply must. Yet, the rules say nay. Surely, this must constitute an instance where the rules are no more than guidelines, where the writer's instinct for the written word takes precedence.