While in the Sell window of the Gold Auction House, I noticed an item in my stash, which appeared in red and could not be sold. It was amongst some other items, which I received in-game from another player. I did recently re-arrange items in my stash, so it could have been moved from elsewhere in the stash.
When I looked at the item in-game, it appeared as an "Account Bound" item. This means that it was crafted by me sometime? Could the other player have given me an Account Bound item? He just dropped items on the ground for me to pick up — we didn't trade them officially.
Best Answer
No, the other player couldn't give you an Account Bound item. Neither could you pick up somebody else's Account Bound item.
There are 4 ways you could have one of them:
Hope it helps
EDIT
Totally forgot about one more way to get an Account Bound item. If you have a special version of the game(Collectors Edition for example), you will be granted 3 Account Bound items:
It seems like you can also get some exclusive items by registering special versions of other Blizzard games, but I do not have any information about it