Are you sure that the shield is black? Perhaps your quiz has only been printed in black and white. A sheaf of corn is a garb in heraldry, and they are usually gold, which is or in heraldry. Black is sable. I've tried googling for images with garb or and sable, but no luck.
Does the logo on this wiki page look like it? http://en.wikipedia.org/wiki/Cheshire_County_Council.
It would fit your description perfectly, as the sheaf does appear to stand in front of the shield, rather than being on it, as in a coat-of-arms. Apart from being blue.