When I hunt parks, playgrounds and athletic fields I'm usually looking for jewelry first and coins second. I've used a lot of different detectors for a lot of years when hunting jewelry, including the Lobo ST, several other Tesoros, Garrets, Minelabs, Compass and others, but the best I've used, still use, is the Goldtrax Treasure Baron. I use the 6X9 coil, turn off the iron audio in disc mode, set it to give low tones on nickels and a high/low tone combination on tabs and run in all metal mode at turn on presets. In all metal mode iron and tiny foil gives a staccato audio response and lights a red LED, thin gold chains and bracelet can also give the staccatto response but it's a softer, fluttery sound than iron or tiny foil. Rings and coins down to around three inches give a fast, hard hit in all metal mode, so will tabs but if you don't want to dig them you can set the disc mode audio to give the dual tone on them and weed out most of those except broken or bent ones. If there's no signal in disc mode, the target is between the nail/salt water range and medium size pieces of foil. When I get a fast, hard hit in all metal mode I lift the coil and swing over the target with a fast sweep speed, most foil will give some rather odd audio responses while rings still give the hard, fast response. Some can slaw and most pencil erasor bands give a longer, smoother and weaker signal in all metal mode than coins and rings, so a lot of those can be skipped.
I would never have believed it before I started using the Goldtrax, and it did take awhile to begin to hear them, but with the audio variations it has in all metal mode I actually dig less trash than I did using all the other detectors in disc mode. The rings in the top photo are a few found using the Goldtrax and are typical of probably 80 percent, or more, of the rings I find. Two of them ID as nickels on metered detectors and the others ID in the foil range. The second photo is a mix of mostly gold and silver good stuff with a few of the nicer plated pieces mixed in, almost all of it found with the Goldtrax at athletic fields, schools and playgrounds. The way I hunt is slow, and the constant audio, especially the iron/small foil staccato, gets a little nerve racking after awhile, but it works well for me. The Goldtrax is out of production and hard to find but Mr Bill, who helps keep Findmall forums going, might have one. He can also substantiate what I posted about how good the Goldtrax, and other Treasure Barons, is for finding gold jewelry.