Nice finds tabdog.
If it gets warm enough today I'm going to our local park to do some hunting. This park has been hit hard for many years with just about every type of detector, and every skill level, but I do it because I still find goodies. Some missed by less experienced hunters, some missed by detectors of lower quality, and some that have just yet to have conditions right to be found. It always amazes me when you find something that just seems to have been missed by all those hunter and by all those detectors.
Earlier this year me and a buddy was hunting the same area hit many times by other and ourselves. I was trying out my new Minelab SE and I get this solid 00 29 at only 5-6". I had my buddy bring his Eagle Spectrum over to check the signal, which we always do, and the Eagle read a solid 92 at 5". It turned out to be a 1934 walking half. We thought how the heck could everyone had missed this signal that pretty much any detector would have detected? It happens. That is why we still go to these places. Personally, I think a lot of these missed targets aren't so much from poor hunting technique as from a lack of good coverage of past detectors.
Lets face it, the concentric coils used on older detectors are great, but with the really deep targets, unless you overlap an inch at a time, you've got a good chance of missing targets. The new Wide Scan DD coils have great coverage, but less depth. You can cover a small area your very best and often a different coil will find missed goodies. If a site has deep trash then a smaller concentric coil will find what has been missed by others. If a site has shallow trash the a smaller DD coil will find what others have missed. The right tool for the right job can make all the difference, and using the tool correctly. The TID is simply another tool.
Your park sounds a lot like ours. It's been a city park for 125 years and lots of trash. The difference for me was it took the right detector to open my eyes. After hunting this park for years with nothing but a few wheats to show, we figured it had been worked out. When I bought my Eagle Spectrum in 1991 it changed this place forever. It was virgin territory below 6" and for the next 5 years it was dream land. Most of the simple stuff is long gone, with the exception of an occasional surprise like the half mentioned above, and now I'm looking for advancements in technology to strike once again. What is really frustrating is recovered over 2000 old coins from this park since 1991, but only a few gold rings. I've hunted enough of these sites to know there has got to be a boat load of gold waiting to be recovered.