[MunchkinMan]

There is no term "backpack" in the game, so I'm going to ignore that word, since I have no clue what you mean by it. We have, quite honestly, seen 3 to 4 different definitions of that term in the past, so in the interest of not confusing other new players, I would also ask that you not use that term on these forums in the future.

You're not limited to trading during your turn, but the only thing you can trade are carried Items. That is to say, all the Items you currently have in play, even the ones you are using. If it is your turn and you are not in combat, you could play an Item from your hand to carry it and then trade it with another player, but you could not otherwise trade from cards in your hand.