Not plastic free but definitely reusable would be Top trumps packs: we've had loads as they get one every year and they get used regularly. I keep one in my handbag along with a travel dobble set in case we get stuck anywhere. If they out grow a theme we regift to friends/give to the toy tombola at the school fete or charity shop. A set that dh got for Christmas 30 odd years ago is still in play.
Or other card games. There is a great dinosaur one on amazon in a fabric bag. It's basically a pairs game but you're finding all the cards which make up a dinosaur fossil. We also love Chocolate Witch which is a little Ravensburger card game where you compete to be the first to find all the ingredients required to make chocolate.
This year dd (5) will be getting camping stuff as she's just been to her first Scout Camp. Head torch, enamel mug for hot chocolate, travel cutlery set, small fold up day backpack plus another fabric badge for her camp blanket. Oh and big thick socks.
I usually put a jar of dried apples dipped in chocolate in their stockings and there would be riots if they didn't get a chocolate orange.
Toothbrush and toothpaste. I try and pick new flavours, last years toothpaste was a citrus one which was a surprising hit for everyone.
A Christmas tree decoration. My 2 get one every year and are slowly building a collection so when they move out, they'll have a box of their own.
A beautiful book working on the same principle as above. By the time they move out they'll have a collection of classic books in special editions. The Minalina ones are particular favourites.