Fossil collecting can lead people into temptation. Roadside exposures are OK for people to inspect, as long as you aren't endangering traffic somehow. In some states, riverbeds are public land and you can prospect there. Private quarries are fine, too, as long as you get permission or pay the right fee. But sometimes it can be too easy to duck under a fence, or dig along a streambank, on someone's land. One nice solution is a public park that gives a little room for folks to pick up some of the abundant fossils and take them home. I've found more than a dozen parks across the country that will let you do that.
If that doesn't tempt you, would a public diamond mine? I haven't been to Arkansas in a long time, but the next time I visit I will make an effort to fossick at Crater of Diamonds State Park, the only public park in the world where you can hunt for diamonds and keep whatever you find. It's just one of Arkansas' geological attractions and destinations.