Waltogirl - nasty, isn't it! Get a pillow inner made of stiff foam, which won't bend much, and which is a bit wedge-shaped. Sleep with the thicker edge under your neck, so your head is in line with your spine ... it's the neck being out of line all night that makes it stiff. You'll get used to it after a few days, and probably sleep better.
Many factors can make your neck stiff when you wake up. Try changing your pillow your head should be able to make it's natural arch back. Stress can cause a stiff neck, lack of sleep or even constant tossing and turning. Hope this helps you find out how and why you wake up with a stiff neck. Also try going to get a massage a deep tissue one or see a chiropractor they can usually diagnosis why your getting a stiff neck and help you feel better faster! Usually after one session you feel a world of difference!