I was under the impression that banks in the USA didn’t deal with forigen coins and only paper notes? I know that up to 4 weeks ago in several banks in CA and TX they didn’t stock any euro coins.
Probably the easiest way to get all the foreign change you want would be to hang out at the airport and offer to exchange it for US money at the going rate. (don’t know if it’s legal, but it’d work)
Most airport/rail station/etc… change kiosks only take bills, and then they rip you off horribly in the process.
Every time I’ve come back from a European country, I’ve always had a pocketful of change I couldn’t get rid of. I’d have happily traded with some random dude for a couple of greenbacks or some quarters, nickels and dimes.
If you have the cash, eBay. I got a set of all denominations of Germany Euros from a seller in Germany itself. They were wrapped very nicely in tinfoil which was wrapped in pages from a magazine. The only problem was he addressed the envelope to the state of “New Jork,” but it got there, so what the heck.