I have a lot of luck around old trees. I found two mercury dimes last month around this tree, and yesterday I found a Buffalo Nickel around the roots of the same tree. What I do is swing almost parallel to the trunk in order to get as close as possible. I also use my smaller 6" coil around the roots. Yesterday, as what usually happens, I will find a coin between the fork in the roots. Seems to happen a lot. I will get my smaller coil as close as possible and then take my Lesche digger and sometimes a probe to pick between. When you know it is a coin down there, you have to be extremely careful and work slow in order not to scratch the coin, due to a lack of digging room. I also seem to have better luck at burrowing under roots rather then cut roots. Seems like roots pull up coins from below.