We do Ferngully's poem too.
So always a book.
Always sweets AND fruit (growing up it was a red apple, green apple (Granny Smiths), orange, mandarin, banana and kiwi each - which was great as usually we only had Golden Delicious apples at home).
Something useful and practical - new knickers or socks, hair bobbins, toothbrushes, or things needed in school pencilcases are great filler-uppers.
And then a few nice trinket-y bits. Bottle of bubbles. Loom bands or the shaped elastic bands. Small cars or a dollie outfit. Rub-down pictures. A decoration for the tree.
One of those fun things, if possible, being something to keep the DCs busy for an hour or more on Christmas morning always helps. Eating sweets (and fruit) while playing nicely before dragging parents out of bed - what a bonus! (DD will drag us out after a while, but is happy to play with something once she has shown it to us and has some food available instead of making us get up at stupid o'clock like 5am!!).
A few things from a list I made some years ago (ideas from another forum, for kids and grownups alike - I'm picking mostly kiddie ones but sorry if a few odd looking ones are in, and it is from a mostly American forum so some slight oddities in wording....)
Book mark
Small toys
Kite
Small game /travel game
Deck of cards
Themed card game
Action figure
Small dolls
Hot wheel s
Yo-yo
Slinky
Silly putty or play-doh
Sidewalk chalk
Silly straws
Small lego sets
Happy meal toys
Army men
Plastic dinosaurs/jungle animals
Doll clothes/Barbie clothes
Glow Bracelet
Bouncy ball
Small jigsaw or sliding puzzle
Brain teaser type puzzle
Rubiks cube
Character band aids
Character toothbrush
Flavored toothpaste
Fingerpaints
Bathtub crayons
Toys for the bathtub
Juice box
Drink bottle/cup
Baby toys/teethers
Gel pens
Markers
Art supplies
Foam stamps
Word search/fun pads
Piggy bank
Marbles
Small cookbook
Holiday shaped/scented soap
Bottles of craft paint
Modeling clay
Beads
Can of soda, Monster energy drinks, Gatorade etc.)
Accessories for ipod….skins, earphones, car charger etc.
Baseball
Small Football
Hockey puck /glow in the dark street pucks
Package of trading cards
Sports water bottle
$5 gift card to coffee shop, Target, drugstores, etc.
Unusual pen or pencil
Magazine of hobby or interest
Gloves
Scarf
Cd cases
Cookies
Night light
Stuffed animal
Chopsticks
Poster
Guitar strap
Guitar picks
Sheet music
Seeds for garden