The National Audobon Society Field Guide to North American Fossils is a must have for any rock collector. The fossils that my daughter and I have found in river beds and other places have been fairly easy to identify using this guide. Of course, it's not completely comprehensive, but we've been able to ID the majority of our finds (probably 90% or more). It contains great photos and concise information - great for the amateur collector. I think it's a great addition to the library of any science enthusiast with an interest in paleontology. The National Audobon Society has many other field guides as well. I recommend using this one in concert with the North American Guide to Rocks and Minerals. It makes it much more fun for your kids when they may actually be able to identify the cool rocks and fossils that they find.