If you’ve been thinking ahead, you have probably been taking non-essential items home with you since you put in your official two-week notice (more details here). If you haven’t, there is still time to catch up.
The most important thing to do first is see if you can get your hands on one of the most coveted items in the office: a copy paper box. If you can get the lid too, take it. You won’t regret it, especially if it is raining.
Non-essential desk items should be going home with you every night. This includes any knickknacks or personal items you don’t use daily. For me, this includes the snowman coffee mug (with top hat lid!) and the birthday hat from Chevy’s. Use your judgment here. It is easier to take a few little things home every night than it will be to pack everything up on the last day.
Make a list of every place in the office you have items. Don’t forget the refrigerator and any common areas. I still miss the lunch box I left behind a few years ago. Please, don’t repeat my mistake.
On the last day, pack stuff into the copy paper box as you use them for the last time. If you are able to, try and do a majority of this while everyone else is at lunch so as not to cause too much of a distraction.
Your desk was (hopefully!) clean and empty when you arrived. Try to at least leave it in the same condition.
Fair warning: Do NOT, I repeat, do NOT take office items that are not yours. Do you really need another stapler or tape dispenser? I think not. This theft reflects poorly on you and may leave your past employer with a bad memory. After all the hard work you’ve done to leave on a good note, don’t ruin it all by taking something you don’t really need.