As a kid, I collected stamps, seashells, rocks, fabrics, feathers, yarn, embroidery floss, porcelain figures, candy wrappers, and I'm sure more that I can't think of. Now I collect earrings, buttons, sea glass, and glassware. Still collect fabrics, but I actually use them now - slowly working through my stash!
So much of the excitement of collecting things back then was never knowing when you would find that exact piece to fit into your collection. It's a lot easier now just to be able to go online and order stuff I try to make it a point of never buying anything online for my collections - the vast majority of it came from spontaneous finds at yard sales or thrift shops. (Well, except the sea glass, that I found on the shore. )
What do you like to collect?