Whenever you go out on a ride or a rally, you probably want to pick up a souvenir of some sort as a memento. People do it all the time, even non-bikers on vacation. But when you're on a bike, you have limited storage space. Even if you have a trailer or a sidecar, you're still going to be limited as to the size and amount of souvenirs and other items that you can purchase. However, that doesn't mean you shouldn't by any little gifts and mementos while on your biker trips.
There are many little biker souvenirs out there that are perfect for those with limited storage space. You'll find merchandise with state and even some city logos at many locations. Some bikers like to collect something from each state they visit. Pencils and pens are easy souvenirs, and they're very small, too. Another small and easy to carry item is a magnet. You'll find a ton of different magnets with different images and phrases on them. Bookmarks are another good, small, and fairly inexpensive souvenir, and they're also useful.
Bikers may be interested in picking up biker patches as souvenirs. There are patches with state names, flags, and logos on them. Plus you can find other embroidered patches with fun designs and images that you can use as mementos and souvenirs. Biker t-shirts and other biker gear can also make for good souvenirs, although they do take up a little more space. T-shirts, however, can be worn right away, so you can always wear your souvenir home if it won't fit in your saddlebags.
Finally, if you do find something large that you absolutely can't live without, you can always ship it home. Yes, it will cost you more to mail it, but if you really want it, it might be worth the money.