Reverse test garden?

I'm just getting back into detecting after a long hiatus. This time I want to approach learning and detecting in a much more systematic fashion. Thinking about building my test garden brought up a question for me. I've seen many testing machines in their test gardens using coins or 3 ringers, etc. Does anyone have typical trash items like a rusty nail, screwcap, pull tab, aluminum foil, etc in their gardens? If so, is this helpful? I'm thinking it might be helpful to not only be able to test on the targets you want to find, but those you want to avoid when possible.

I am planning my test plot layout over this winter and I will be including common trash items, co-located good & bad targets at various depths and separation distances, and a selection of old and modern coins.

Some do,yes,and that’s a great way to think about things. Most of the time,with the uncanny abilities of the CTX,if it gives me little hints that the target might be a coin,I’ll go after it,especially when deep. Depth has always been a “hot seller” when it comes to new detectors but it’s becoming clearer by the day that we are missing a lot of good coin targets because of ever increasing trash in the ground. Knowing some telltale responses from common trash items will help you for sure,just make sure to spend as much time as possible HUNTING. There is always an abundance of “theorizing” and “postulating” and “testing” and so on. While that can be productive in the right quantities,NOTHING will re-teach you detecting like,well...detecting!
Welcome back Mr. Hole!

You want to have complete control of your test garden, in other words, you do not want any metal in there that you don't know about. As Tom D. recommends... sanitize it first with a detector no disc, and then use a earth magnet to remove any iron.....makes a whole lotta sense doesn't it?

True that Ozzie,
As Tom has pointed out you have to start with a known "control" as a benchmark.
I bought a 1200lb rated rare earth magnet for sanitizing and magnet fishing.
Cheers,
Drew.

Good idea common junk items from your area ought to do trick...and make a map as one forgets over the years...had one myself for over 20 years but just silver and clad..