GPS-ing Ploughed Fields
Here is a short explanation as to why we (Dad & I) think its a good idea to GPS significant finds (this includes most coins & artefact's Medieval & earlier, plus some rarer 17th century stuff):
Most of our best fields have been cultivated since late Bronze Age/Early Iron Age & continued to be farmed into the Roman period & so on. These fields archaeological layers have been messed with for some time. The deeper undisturbed layers will from time to time be ploughed up by modern deep ploughing.
I only detect the ploughed soil & guidelines encourage me not to dig in archaeological layers which I respect.
Some might ask: "Why GPS in a ploughed field, as its probably moved some distance from its drop point?"
Here are examples of that happening:
Soil brought in from miles away & dumped on the land.
Soil dropping off of combines wheels (they carry a ton of soil on all 4 wheels)
Sticking to the plough & dropping off
Soil slippage on hills
Magpies picking up shiny objects

& so on....
So why GPS?
1) The Saxon Brooch is a good example. I found one third, Dad got another & the last bit is still out there (I hope). They were less than 2 metres apart & the break was healed so its not a recent break. Without GPSing finding that spot in the middle of the field would be very difficult.
2) For items that fall under the Treasure Trove Act, I can give a good grid ref. I'm only required by Law to give a six figure reference but I like to be more precise.
3) We have done the most detailed detecting survey ever for our local area. This can be later studied after my death & is useful when planning construction work on the land.
4) The farmers like to know where the finds come from, particularly the ones I have given them. So they get detailed maps of the finds.
5) I can track back finds & coins to the places I found them.
6) Many items do not move as much as you image, specially on the flat fields we detect. So we can study consentrations of finds & even patterns (like linear features, or long gone field boundries). Clearly this will help target future years searchs.
7) I help book writers with there research & they really appreciate this level of detail.
8 ) A whole bunch of historical reasons
There are a few more to, but if anyone can convince me I wasting my time then I will happily stop?