Panem isn't a place where Christmas is celebrated and even if it was, District 11 is pretty poor. That said, if Rue finds out about Christmas or gift-giving in general, the following people will get items.

Katniss: Whatever arrows Rue finds in the weapon shop (or she might request some), and a woven grass charm similar to the one she had in the arena.

Prim: A woven grass bracelet (think friendship bracelet). Also some balls woven out of grass for Buttercup.

Richard: To be determined!

Peeta: To be determined!

Any other people Rue might get to know better between now and Christmas will also get bracelets or charms made out of grass.