Gifts for people who already have everything
The problem is rarely that they own everything. It is that they buy their own things promptly, which rules out the obvious and points at three categories that still work.
Gifts under twenty dollars that do not feel like it
A small budget is only a problem if the gift is trying to be a bigger one. Where twenty dollars buys something genuinely good, and where it buys a compromise.
Buying a gift the day before
Short notice is a constraint, not an excuse. Which categories survive being bought in a hurry, which ones announce themselves, and the two questions that narrow the choice fast.