Any place near your home . Look at satellite map of area you live in and pick out the fields schools and parks you want to try your luck at for those hunts you don't have a bunch of time. The list up above, and anyplace you feel like you can get away with swinging a detector. Some places, like the ones on the list, will usually have a greater concentration of possible targets. These kinds of places will also have t he greatest concentration of treasure hunters. I have found modern coins every place I have ever detected. I didn't start fining silver until I started hunting baby boomer schools. Luckily, a lot of schools were built when WWII was over and people celebrated by making babies! probably the best hunting grounds, will be had by getting permission to hunt private grounds. Doing a little homework on the history of towns will turn up some good possibilities . The local historical fort may have been relocated at some point in time, old military camps were the beginning of many towns and town may have been built in different location from a towns humble beginnings...... Any older part of town they are owing street or sidewalk removal is like a time capsule and once replaced , won't see the light of day again for a long time. I have even scanned in random fields that weren't , to my knowledge, any form of social hot spot at any time in history and still found pesky pull tabs and a modern quarter. If there is older trash, could be older coins to be had.
My first older find was at my local fairgrounds in the overflow parking area that is nothing more than a flat field they use for parking during the fair. It was the driving range and club house area when I was a kid. They had skimmed the the top with a dozer and began bringing in recycled blacktop . Half the lot had already Ben recovered so I half heartedly swung my detector on full stride on my way to the dirt pile in the middle of the lot. Even swinging the coil wildly and way to fast I managed to hit two signals on the way to the dirt pile. One modern nickel and one tax token from 30-40's. On the dirt was a thick brown piece of a bottle bottom. It was from a Clorox bottle from the 40's. Didn't find anything exciting in the dirt pile but it exciting to get on some older stuff. Perfect timing as I May not have found the token if bull dozers hadn't removed the overburden for me.