When we're talking about collecting data for worms and where to collect the data you start thinking about good locations and that’s an easy answer, you could collect worms in any location as long as there’s soil.  There’s many different types of soil and different type of worms, I think going somewhere where it is wet gives you a better chance catching worms, and the ground should take the water better and not have any run off. You could even do this in your backyard and that would be a good location, also make sure the ground you're doing it on is even so there’s no run off