Continuing my clean out of a folder with some older pictures, here are some Trilobites from the Wheeler Shale near Delta, Utah.
These first few specimens are Agnostid type trilobites which are fairly common in some layers of the Wheeler Shale. I believe these are called Peronopsis interstrictus. I collected them about six years ago from an outcrop that was teeming with the little guys.
Next up is a large (2" long) Elrathia kingi that popped off the shale matrix. This is somewhat common, especially if the shale is weathered a little bit. The trilobites are preserved with Calcite which is a bit tougher than the soft, layered shales they are contained in. I purchased this specimen and the next one from West Desert Rock Art, a small rock and fossil shop in the town of Delta, Utah.
Lastly we have an Asaphiscus wheeleri.
The three trilobite species shown above are the most common fossils in the Wheeler Shale. There are dozens of other species that can be found but some are more rare, or restricted to certain layers within the shale. The Wheeler Shale dates to the middle Cambrian. Here is a great page from Trilobites.info concerning the Wheeler Shale.
The fossils are so abundant, and exposures so easy to find/mine that there are a couple of fee quarries that you can try out while in Delta. One, that I have visited, is U-Dig Fossils. If you follow that link to their web site you will see that they now offer a service where they will ship you some of the fossiliferous shale that you can split at home. A fine alternative if you can't make it out there yourself.