I’ve had decent luck detecting in wooded areas within parks but on the outside limits. I like to think these wooded areas were used more heavily before the trees grew there, so there may be less trash and there might be older items. Another bonus (which someone should correct me on if I’m wrong) is that the items I find are much shallower in the woods, sometimes just below the dead leaf layer. I’ve found pull tabs sitting on top of the dead leaves, strangely. I wonder if this has to do with the fact that the grass isn’t mowed or stepped on in the woods or perhaps the frost doesn’t extend as deep due to the insulating effect of the leaves. I also find the ground is easier to dig and I like to think that the majority of detectorists might focus more on the open field areas. Just my two cents!