M&S have got a miniature green wheely bin desk-tidy - I put one in each of the dses' stockings last year. Generally they get toiletries, chocolate, socks and underpants, and a clementine.
One of the most successful things I've put in, in recent years, was hot choc mix (from thorntons) and mini marshmallows or squirty cream, so they could make themselves posh hot chocolate. That went down really well - this year I am giving them the mini marshmallows and the squirty cream, as we have lots of hot choc powder in the house.
I have just been counting and listing the DCs' stocking presents.
For 18 year old DS, I have got some spices and sauces (he likes Asian food), some silly underpants, a cool pencil case (he is a student), a flag (for his room, from the country he was at school in), a mug, a drink, a silly post-it notepad, a turned wooden bowl (he likes the texture), an umbrella (from his old school), a calendar. I shall add a few more things, like toiletries. Anyway, nothing here might be relevant to you. I just keep buying small things as I see them.