When I was eight and we lived near the bush, it was special rocks and twigs. And tadpoles. And marbles.
At ten and eleven, when we lived in Tokyo, my brothers and I would go to a tiny but amazing model shop near Roppongi. The owner was an amazing model maker and always had awe inspiring scenes set up in his window. Inside was stacked to the roof with a comprehensive selection of plastic model kits. We used to buy and make aeroplanes (Spitfire was a fave, and the Stuka with its bent wings), tanks, and less often, a battleship or a destroyer. I was never that keen on the toxic smelling and hard-to-get-off-fingers adhesive that came in a tiny silver tube but I would diligently assemble a small army collection. What I loved most was painting them and putting on the decals - which needed pre-soaking a shallow dish of water and very delicate and precise handling.
Around thirteen I discovered the splendid and rewarding joy of reading books. New paperbacks (in English) were prohibitively expensive but I soon discovered a shelf or two of English language paperbacks in some local Tokyo bookshops. Again, the shops were narrow and tiny and crammed with merchandise. My area of interest and focus were up the front on the right of the Hiroo shop, down the road from our house. Just two or three shelves worth, each less than a metre wide. I would visit often and study every new book, considering it's value and possible reward. I really disliked buying a book if I wasn't going to read it, so I selected carefully, often reading the first twenty or so pages while standing there, sometimes for an hour or more before choosing. Luckily, in Japan, tachiyomi (literally standing/reading) is common and not discouraged by shop owners whatsoever. I would get out my fifty or a hundred yen and pay for my new treasure. The library at school was OK when I was younger with things like the Hardy Boys series (much loved!) but had nothing that would fast track the development and maturing of a hungry and curious teen. A few authors that spring to mind are Alistair MacLean, Roald Dahl and John Fowles. I would also read some slightly raunchy and macabre B grade novels - about witches, fighters and promiscuous experimenters. I was well known for carrying a paperback everywhere in the side pocket of our school blazer. Two other kids, Zac Callahan and Chris Styles, also started doing this and we would often check out what each other was reading and talk stories. Most of the other kids in the class associated reading with school work and shunned it. For us it was a doorway to new and exciting worlds. I'll always remember the feeling of finding a really good new book in the shelves. And the joy of reading one - wanting it to never finish. The Magus by John Fowles was an especially thick one and satisfyingly lasted for quite a while. I considered it a masterwork of the imagination. He also wrote a book called The Collector.
Part of the satisfaction of collecting is the thrill of knowing your subject, area of interest well and becoming familiar with all the popular and semi-popular items within it's realm. Then what happens is every time you go out seeking additions it becomes increasingly harder to find something new and worthwhile. You either have everything good or at least know about it and don't need to acquire it for reasons of taste or space. When you collect you are honing your knowledge and developing a personal taste and quiet opinions about the things within the microcosm of your passion. It's a very healthy and nourishing thing to do. I learnt a lot about art and developed my taste through collecting comics and album covers. I never bought new ones of either of these groups, preferring the chance and thrill of second hand hunting expeditions.
Other things I have collected over the years: movie posters, magazines (especially early Esquires and National Lampoons), film scripts (ordered by post from LA), poker card protectors, hippy necklaces, stickers, caps, skulls and bottle tops.