Confession: I still haven't finished all my neighbor treats. But. I did manage to get a few done, including this one for a friend who is gluten-intolerant. She loves peppermint patties so I gave her a jar full of those. You could do hot cocoa mixes, cookie mixes, soup, etc.
I had bought some chalkboard paint for another project, and I still have a ton left over. If you want to do it, it's pretty self-explanatory. Paint the lid with 2 or 3 coats of paint and write a message on the top! You can decorate the jar too if you want, of course.
And a little tip I saw on Pinterest after doing this, you can sharpen your chalk in a pencil sharpener for more precise writing.