The trilobites were found a little bit west of Delta, Utah. There's one rock shop in Delta, and the owner has a claim where he finds them to sell in his shop - he's a very nice guy, and he's more than happy to let you pick through the rock piles he's already looked through, all you have to do is go to the rock shop and get a "permission slip"! His brother has a pay-to-dig spot right next to his claim, but why pay when you can find just as good of stuff for free, right? I definitely recommend checking it out if you ever happen to be in west central Utah - I only split shale for a couple hours and found at least a dozen whole trilobites, and countless pieces - it was a lot of fun....