Not just cornfields, any fields! We have fields around out house that have been there for a very long time. One field used to be a baseball field years ago, and I found several wheaties where they had some bleachers there. You never know what you will find in a field. One field in Connecticut produced several old coppers. In one of the fields Vlad found a cowbell. In a field we detected in New Hampshire, I found a 1800's iron toy train engine. It is my favorite relic. After doing some research it looks like it is an 1863 model cast iron toy train. Some people search fields looking for arrowheads. I haven't ever found one, but have met some people that have great collections.