I thought it unusual that leeneia says she has only the vaguest idea what a porcupine is like. I thought porcupines were common. But then again, maybe not. I recall seeing a porcupine in the wild only once in my life - at Boy Scout camp in Northern Wisconsin in about 1965. I've seen lots in captivity, though.
We don't have hedgehogs in the Americas, and I've never seen one in the wild. Wikipedia says that while they are spiny, they are not related to porcupines (but both are rodents).

-Joe-