I've got a lot of coins accumulated as leftovers from time overseas myself...predominantly Deutschmarks, Israeli sheks, various countries' dinars, some Euros, Dutch guilders, even a Honduran lempira note...all kicking around here somewhere. I don't regard them as having any more than sentimental value. Also a bunch of US coins my Dad collected, mostly unsorted thoug some were carded, talked to a collector about having them appraised for the estate, he told me that kind of gaggle basically goes for the scrap price of the metal and nobody would go through them for an appraisal fee, plus even if there was a pearl in the pile, there's always the risk the appraiser would pocket it.
I keep a cigar box of worthless money from my travels. It started as an amusing anecdote from traveling in Poland in 1995 when they were transitioning from the złoty (or
stare złoty, literally meaning "old money") to the "novo złoty," translating to "new money." Short version: there had been so much inflation post-Iron Curtain that the Polish government eventually just took the existing currency and lopped four zeroes off of the end. But there was still a bunch of the old currency in circulation, so you had to be careful because you could easily wind up accidentally paying $50 for a bottled water instead of 50¢. At some point, I managed to wind up with a 5 stare złoty note, and with some bemusement, we sat in a bar one afternoon and calculated that it
literally was not worth the paper it was printed on, that it would cost more to physically create the cotton rag, ink, etc. to produce that note than it was worth, a tiny fraction of one US cent. So I started keeping other such "worthless money" from other places, none quite so utterly valueless, but similar. I have a one-kopek coin from St. Petersburg that, at the time, was worth something like US$0.00025, for example. For the most part, it's either old Soviet or post-Soviet currencies or otherwise discontinued currencies (Deutschemarks, Francs, etc.).
I keep it around for bemusement's sake. It's the functional equivalent of collecting Confederate currency: makes for interesting conversation pieces, but little else.