My wife and I used to go field walking with an archaeological group. The field was divided into 10 metre wide sections and each of us zig zagged through each section. Anything of interest we uncovered, we would mark with a flagged stick, and other people with a GPS would examine, and, if of interest, they would locate its precise position and take notes before lifting it from the ground. There were plenty of finds, mainly old pipe stems, and bowls, but also shards of Roman pottery, or even Anglo saxon pottery. I was lucky enough to find a Neolithic flint core stone once(a stone used to produce flakes of flint by Neolithic settlers), and, someone else found a perfectly formed flint arrowhead, which we all gathered around to see, before it was collected from its original spot. Some of these 'finds' are on display at a museum in Scunthorpe. We loved doing this, especially on a sunny warm day, because you didn't know what exactly you were going to find. I would recommend it to anyone.