Picture posting is enabled for all :)
Current best hope is that it came out while filling the tomato or aubergine tubs.. we empty them out at the end of the season to reuse it for carrots and other roots..
The weirdest thing I've found was a .303 bullet case that turned out to have been manufactured in the 1960s with a wooden head for machine gun practice - The other plot is only a plots-length away, nothing of the sort, yet I turn up prehistoric flints there, but never on the other plot. Make sense of that.
Thankfully we don't have the same problem with un-exploded Ordnance that the former Western Front has!