I am covered in scars, most of which I don't remember the origin of. I have a cool hourglass shaped scar on my left pointer finger, half of which came from a plastic box, but I'll be darned if I know where the other half came from. It's been there as long as I can remember. I also have a scar in my upper lip, from where I fell off of a sea wall and bit clear through it as a child. There's plenty more from my childhood, but they're minor, and I have no idea where they came from anyway.
The two that stick with me the most, though, are a scar on my left pinkie finger, and a scar on the webbing of my right ring finger. I earned both of them during my Freshman year of college, so they aren't exactly childhood, but they are notable. The first one happened when I managed to slice the tip of my pinkie off, except for a tiny bit of skin, with a cardboard box that I was cutting up. Before you ask, no, it wasn't the box cutter; it was the worst paper cut in history. We reattached it with steri-strips, but it never healed quite right, and there are times when I'm afraid putting too much pressure on it will break it back open. The other scar involved me walking into the sharp edge of a gas grill, and cutting myself in such a way that it would heal without stitches, but I wouldn't be able to play guitar until it did heal. Well, I had already taken a couple of weeks off of practicing for the sliced off finger tip (I was a music major at the time, not practicing was a bad idea) so I couldn't really afford more down time. I went to a walk in clinic, got it sewed up, was able to play while it healed, but wound up with a worse scar than I would have earned if I had just let it heal on its own. The things you do for your art, eh?
Edit: I forgot my most noticeable childhood scar. I have a perfectly round scar exactly centered between my eyes, looking for all the world like a Hindu caste symbol. In reality, it's a chickenpox scar that happened to wind up in an odd place, but people tend to notice it.