DetectingWales.com

 Had a couple of hours out yesterday  in the potatoe field that i spotted being planted in the spring, only a couple of rows lifted though,  so went around in the stubble on the surrounds,
 found a George 4th Irish halfpenny, 1822.
 
 but then a large signal, dig down 2 foot  to find some rusted metal sheet, on the side edge of this i found what looks like a cartwheel penny,  hmmmm,
 
 i cleaned off the sheet with my gloved hands  to see a couple of holes in it, looked to be cavities under it,  so set about cutting through it,  could it be some sort of buriel i thought,  i dug my spade into the soil underneath to see how firm of soft it is,  my spade went down remarkable easey,  so i cleaned it out with my hand  to reveil a larger cavity,  couldn't get enough of my arm down there to go right in,  tried digging more out, but it got too difficult, not enough room, but i saw what looked like rotted wood on the side wall too, about 4" of soil underneath  before the cavity,  down about 3 ft now,  didn't have time to dig around more,  so had to fill it all in again,  if i'd have found some bones or coins i would have just put it on hold.
 
 My Bonus for the day though was about 30 lb of potatoes or more that i picked  that was left behind,,  a bag of Elderberries and a bag of blackberrys to go with a load of apples i had given me  for going up and pickling a load for a neiboure,  Apple crumble ect on the menue soon, lol  pehaps i should get out and get some more elderberries and black berries soon for wine, hic, hic,

The coins

Your find reminds me of one I found many years ago that nearly took my eyebrows off, it was tin sheeting with a thin layer of soil under it and very soft earth or a cavity under that, I was sat pondering whether it was worth digging as the tin had obviously been the target, when I lit a cigarette and threw a match in the hole....................whooooooooosh!!!!
The flame was to say the least......impressive.
Asking about afterwards I found out that it was probably a field toilet from pre mechanised farming (only pre 50's) when you had a lot of workers picking crops. I had released a pocket of methane.

wow,  Thanks Geoff,  i bet that made you jump,  lol. i wonder if mine was the same, i didn't have time to go and ask the farmer if he knew anything about it,  if a hole had been dug  to bury rubbish ect,  sounds the same though, under that couple of inches under the sheet it went down Quite soft too,  i nearly lost my shovel when i stabbed it in lol,
 i did stick my nose  down there to see if i can smell anything bad, like rotted bodies lol,  nothing though,
 it was the large heavey  coin i found down there that kept me going a bit more,
Alan