Ditto car wash booklets.
For actual gifts you can give small non-food items like lip balm, hand cream, gloves, etc.
If they have hobbies that you are aware of you can often find a lot of good stocking stuffers at the hobby store.
My grandmother likes to knit and I give her stitch markers, stitch counters, and needle caps since she's always losing hers!
I would avoid food items unles you know for sure what the person does/n't like or can/'t eat.
If they have pets then pet toys and treats are always good stocking stuffers.