Yes, I've had some good experiences with junk trays at car boot sales, markets and in shops that aren't specifically coin shops (often second hand furniture or book shops, where they get random lots of coins along with whatever it is they're actually interested in).
Some that stick in the mind, in case they're still there and are of use to other people:
– Several of the WW2-related museums on Guernsey, housed in concrete bunkers and other suitably dingy locations. From memory there's one within walking distance from the centre of town, out along the coast (can't remember which direction), and another out by the airport somewhere.
– Glance Back Books in Chepstow, Monmouthshire. This sticks in my mind both for being a source of 10p-each rummage tray contents that included things like silver Swiss 5 franc coins and other things that were worth a sight more than 10p, and also for the hilariously xenophobic and anti-Europe views of its proprietor – notable even by the normally high standards of the UK for that kind of thing. However, I think the guy who owned it had some kind of bust-up with Monmouthshire county council and closed the shop to concentrate on selling books and xenophobic poison by internet.
– Street markets in Hungary, specifically Eger, but also some just at random points on roadsides. I suspect such things are gone now, and the locals probably have a much better idea of what tourists will pay, so the bargains won't be so common.
– Ditto in Kiev, and this was more recently, so might still be active.
– Large antiques fairs in the UK, such as those held at the Donington Park motor racing circuit and Newark racecourse. I mention these specifically simply because they were the nearest to where I used to live. They happen all over and because the stall holders generally have more mainstream antiquarian interests, any piles of coins tend not to have been sifted for rarities (other than perhaps having had the silver removed, which will be on sale at the silver price).
