"The Audubon Society Field Guide to North American Trees" (eastern region) has color pictures of; leaves, bark and acorns along with some great info. I have been taking my copy to the woods for years and love it.
One of the distinguishing characteristics of the white oak acorn is the cap. It tends to be rough with what looks like a jumble of tiny little beads. The caps of other types of acorns tend to resemble scales.
Thats my best shot...wish I had a scanner, I'ld zip you a pic.