We had pillow cases growing up, and stopped beyond a certain age, though mum always got all four of us pjs, knickers/underpants and socks every year and now she's gone we (siblings) do it for each other.
But my DPs lovely mum does stockings for everyone including me. Last year mine included:
Sweets
A canvas shopper bag thingy with a wuthering Heights reference - it was from Booths but there are usually various ones for £1 in primark
Nail polish remover pads
Hand cream
Emery (so?) boards (my main present was an OPI gift set so these went with them)
Travel size toiletry bottles
Hot chocolate sachets
Mojito flavour lip balm
My favourite gel writer pens
DPs was:
Sweets
Nuts
Scratch card
Body wash
Chilli sauce
Key ring of favourite beer from local brewery
Paper aeroplane kit
Pub quiz book
Could you make/print some cards with some quiz questions on, or challenges/dares of some description, list of words they have to work into conversation at dinner, whoever manages it gets a prize (a quality street or similar) as long as nobody realises that's what they're doing. Or riddles/dingbats etc - whatever you think would go down well. Just a quiz answer sheet with instructions to bring it to the get together and you'll do a quiz.
Sparklers?
Slinky - for slinky races
Alcohol miniatures
Badges - could you get some ordered with something relevant to each person, you know the sort of 'head girl' thing? Or a reference to a family joke/funny story etc, though might be too hard to think of one for everyone!
Those photo prop kit things - you know on sticks, range of hats, moustaches etc - could just get a couple of kits and divide between the stockings, then they can be used for photos on the day.
Hand warmers
Face mask/sheet masks. You can get big packs of the Korean beauty ones on Amazon - even the men might like a pamper!
Car air freshness
Homemade goodies - I do nigellas Christmas rocky road for family/adult gifts each year (along with either cranberry or Christmas pudding vodka or similar which I make a few litres of then decant into 25cl kilner bottles).