Welcome Jillmarie. So nice that you want to get your mom a cover! But, while you
can use someone else's code, you're not supposed to. It is against Amazon's terms for the SO Kindles and, as such, KB does not condone such trading.
It is entirely possible that the cover offer will come around again . . . especially as the new Touch and Fire models are just getting into people's hands now, so I'd suggest being patient
But it would be acceptable to use your code to buy a cover which you then sell to a friend. Those sorts of transactions should be handled by PM outside the public threads and it's all entirely at your own risk. KindleBoards offers no liability for such a deal gone wrong.

Also, there is a Buy/Sell/Trade/Barter board a bit further down. . .people do sell covers there. . . perhaps someone has one they're selling that way. Again, the transaction is between the two of you; KB just offers the spot for the 'classifieds'.

Again, Welcome! Check out the rest of the boards. . .there's lots to talk and read about. . . .some of it not even about Kindles!