Not only does blue cheese taste wonderful in quiche, but it's an unexpected surprise for even experienced quiche-eaters. Use any sort of exotic mushrooms you like, but use the caps only, as the stems can be too chewy for a dish like this. I like to use a mixed, 8-ounce pack of crimini, oyster and shiitake mushrooms here, available at my local supermarket. Portabello mushrooms are also good.