The regular gifts are the boosters and skill point, which you can send every day.

to send a jersey is a *very* nice present! You can send any shop bought kit so long as you are not currently using it, have purchased it (not been gifted it yourself) and (this is the tough one) you have to have purchased the value of Tokens for it, though not necessarily got it with those Tokens. I think this is true, but I have been unable to send things I have, so I am not entirely sure what else prevents an item from being gifted.