Circle around a standing dead elm, ash, oak or apple tree. Elm is best in my area, one that is starting to peel its bark is perfect. Hillsides or higher ground seem more productive. I've heard old abandoned orchards are good, too, along with railroad tracks. Carry a walking stick to push plants back, I swear they try to hide when they see you coming. If you find a mess of them leave some to "seed" for next year.