We used to collect beach towels but we got too many of them. Then we collected buttons/pins but after we covered an entire wall in the living room we stopped. Now we collect shot glasses and have special cases for them.
Rather than collect a bunch of one type of item ( other than the shot glasses) we now go for an eclectic hodgepodge of items from different places. It is fun to collect things but I must agree that memories are the best of all.