Remembered my school days are mainly what you guys have mentioned;
Primary School
1.) Eraser and sometimes bottlecaps so that we pit our thumb skills to capture those "prized" stuff.
2.) Collected WWF (World wildlife) sticker books, (Think now kids still have this habit of collecting stickers). Sometimes really envious when my frens have completed collection of 2-3 books and I still stuck with 2-3 stickers for that single book.....

Secondary School
3.) Basketball and Upper Deck cards. That time, the most prized ones are the American dream team (BAsketball) (Michael Jordan, Charles Barkley, Karl Malone, John Stockton, Magic Johnson...etc etc) cards which they represented in 1992 Barcelona Olympic Games.
4.) Played Role Playing Games (RPG). Not the ones that is on the computer but actually fantasy role playing games. Remembered used to owned those 4 sided, 10 sided and 20 sided dice. Not really into Dungeons and Dragons (RPG) but more on Robotech and modern RPGs because that time, some western teenager played D&D so much that he thought he is the character and killed his parents. Sad story.
Anyone has done the above as mentioned?