I have accepted another position and my last day of work is Friday. I have about 15 co workers and boss. I work in a mental health agency in a school setting. So I have my coworkers and a school full of teaches and admin.
My questions is... what is appropriate when leaving? I feel like I want to give them something but it seems like a lot of work and feels strange. Is there etiquette to leaving a position?

For your close acquaintances, a small memory trinket on the order of a key fob or bracelet charm might be appropriate. For co-workers, a goodbye hug or handshake should be sufficient providing you seek them out to say goodbye personally.

Nothing is expected but how about bringing a treat in for the whole staff for the break room? Order pizza in if that's not too costly and treat for lunch, or bring in donuts, or bake brownies... you are on the right track to leave on the best terms possible to maintain the friendships, and also the reference!

And after you leave, make a point of staying connected with your boss - send a thank you note for their contribution to your growth and learning in your career, for example. They will remember your class when you ask for a reference later!

Thanks! These suggestions are good. I work for an angency, and there is one of us in each school at a district. So I am not in contact with my co workers daily... but I can do the brownies for my school staff. :)
My boss and I get along, but we have had our conflicts, mainly because she is passive aggressive, she plays favorites and I am not one of them, and she is a new supervisor and learning her role. She is very insecure and gets mad at us staff a lot. So I don't want to burn my bridges and I want to do something nice for her, but I don't want her to make it a big deal and thank her too much because she is part of the reason I am leaving... as well as why others have left. :) Is there a middle? Haha

I would think that THEY would do a little something special for you. A nice send off some kind...
Since I'm posting this after your last day...
What happened? How'd it go?
Hoping the best for you at your new job. : )