Most treasure hunting metal detectors are adjustable to discriminate for or against finding iron. Some treasure hunters use them specifically to find iron artifacts, it depends on what you are searching for and if you are looking for a specific area such as an old dump site or mechanical parts in a field. I found a complete plow under the ground behind my old barn that was designed to be pulled by a horse or mule.
I have never scanned wood with my detector but I will give it a try, I am interested in hoe deep it will find metal objects. My home is about one hundred years old so there are probably metal objects in some of the older yard trees. My barn has some pretty large timbers and lots of the old style square nails.
Has anyone tried a pinpoint detector, the ones used for treasure hunting?