Have found parts of 'hedge' posts, a chunk of rusty 4" channel iron, my 14" Rigid pipe wrench, and yes even rocks. Fortunately not all these were found in one season. Stone traps have worked in all cases except one. Picked up nice 6" granite specimen. Was to big to lay down in trap. It was caught inside the cylinder [no filler plates]. Getting that stone out was a story all in itself.