Back Yard Test Rig Idea

I've been trying to think of a good way to set up a sort of test-rig/test-field in my backyard that would realistically simulate finds in the field for a while. Some days I really want to get out for the practice/fun of it, but don't have the time or energy to look for a new permission or to make it somewhere to detect (I live in a weird spot where it takes 40 minutes to get to ANYWHERE based on traffic and old New-England suburban roads). So here is what I came up with:

I have a wide array of old coins, jewelry, trinkets, and junk from detecting, coin collecting, home renovation, and a wide array of hobbies. Air tests on these items give you some idea of how they will ring up on a given detector, but they aren't all that useful. I could just bury things around my backyard, but that's a pain and I'd likely forget things were out there over time. Instead, I can build a sort of double-decker raised bed planter with no metal fasteners. The top tier would have to have some kind of weed barrier fabric to keep the soil from spilling out, but that's not insurmountable. Drop whatever item you want to test in the bottom tier and squish it down a bit, then drop the top tier on top. Swing away and soak in the sounds of your neighbors going, "what is wrong with him?"

It's probably (almost certainly?) more trouble than it's worth, but I might just build it once I wrap up my kitchen