Location: Along the length of the North Sulfur River near Ladonia. Access the river at any point where public roads cross it. One popular spot is the Ladonia Fossil Park.
What you can find: For the full list, buy the Fossil Collector's Guidebook to the North Sulfur River. Common finds are belemnites, ammonites, mososaur bones and teeth (a very large crocodile-like animal), and shark teeth. Sometimes you'll find more recent Pleistocene animal remains, such as mastodon, camel, bison, mammoth, and so on. Also, enormous quantities of petrified wood pieces, ranging from quarter- to palm-sized.
Ease of Access: Be prepared for a steep climb down into the riverbed. Once in the bottom, it's easy going (if the water is low).
Locality Type: Riverbed / gravel bar
Equipment Needed: Mostly surface collecting. If you're ambitious, screen washing provides some nice finds though.
Additional Information: This is one of the most popular Texas fossil sites, so be prepared for some competition. The further you're willing to walk from a bridge access point, the better your chances are of finding something good.
Fossil Collector's Guidebook to the North Sulfur River
A Field Guide to Fossils of Texas
Roadside Geology of Texas
Gem Trails of Texas