Got an old colleague who does it and he's found all sorts including a load of Iron Age coins: https://www.google.com/amp/s/www.gr...-of-gold-and-silver-iron-age-coins-1-8141254/
You will not find anything more valuable than the ring pulls from cans of Fosters in Aussie land
I'll certainly remember my pals Bertie; I've still got at least 10 fingers...