In the last few years there have been some interesting Devonian aged fossils coming out of Bolivia. I have mostly been purchasing mine from this seller on E-bay. They are found in small, round concretions so you often get a mold and cast of the fossil. Among the fossils I have acquired are some fairly nice trilobites with the most common specimens labelled Eldredgeia venustus; although some specimens could be another closely related genera, Metacryphaeus. The only way to tell them apart is to count the number of lens facets that are in the eyes and by measuring the ratios of the glabellar furrows and lobes (the rounded parts on the head between the eyes).
Here is a specimen contorted into a "U" shape
Another specimen is curled up a little differently
These next two photos are of the fossil's mold....
... that fits perfectly on top of the lower half.
These specimens come from the Belen formation (Devonian, Eifelian stage) south of the capitol of Bolivia, La Paz.