Before I get into the whole memories part, I really want to say try to compare currency exchanges online. The best one around me was with ASDA and we got a really good deal on our euros.
Now for the trinkets and memories, obviously if you are backpacking, it’s not ideal to bring back loads of stuff from different countries, so you could try getting a postcard if you’re in a city, or maybe a bracelet and then stick them in a journal when you get home. As I was only visiting one country I brought pack a postcard, a little ornament and a key ring (which is also a bottle opener, because Belgium, beer). Obviously that isn’t suitable for everyone and will weigh you down if you get one wherever you go. Another good one is polaroid’s, my friend had one so we took lots of them. Or you can just use a regular camera, or a phone. You can print them out once you’re back a really cool app is pologram, they can do scrapbooks, polaroid style, classic, canvas posters. Me and my friend decided to write in a journal of our time away, a way to reflect on the day and recap all of the best moments. You can even keep little things like tickets etc in there to keep. One of my favourite things is the scratch map, so you can scratch off the countries you’ve visited once you get back.