Not a horrible idea, but a bad one and definitely not something you should be doing.
Snacks for the office or as appreciation for the members are the team properly come from what I will loosely call higher-ups. Also, they have expense accounts to handle the cost which is properly borne by the company.
Whether you’re thinking about it or not, you are now developing your professional reputation. Professionals are not spending their brainpower (or their money) putting together treat bags for the guests as if work was your birthday party and everyone there was under ten. You will develop a reputation for not understanding this, which does not bode well for your chances of promotion.
Professionals who hit the managerial level should worry about morale of the team they manage, but the goal is never to create an environment where everyone is “friends.” Now that you are out of school, you are expected to (and would be wiser to) develop a private life separate from your professional life. There is nothing wrong with being friendly in the office and there is occasionally some crossover, but the goals of work should be more focused on getting the work done – preferably as efficiently as possible so everyone involved can go home to their families and actual friends. That is part of the reason socializing at work focuses on lunches and the occasional “happy hour” instead.
This isn’t meant to be bleak – it is incredibly comforting to be able to vent about Chris-in-Accounting or Lee-the-Ridiculous-Temp to someone who is entirely on your side and will never wonder about your professionalism after getting promoted above you.
I’d like to re-target your thinking to focus on two goals – the more you can think of them as separate and distinct, the better off you will be.
Goal 1: Establish yourself with a positive reputation in your office. If you want to get promoted, kick ass on the work side. You should be helpful and friendly (which again, is not the same thing as being friends) to everyone, reserving the right to be merely professional with those who have caused you offense.
Work versions of being friendly include asking SAFE questions of your co-workers without prying or embarrassing them, and then listening to the answers. “Did you have a good weekend / Do you have any interesting plans for the weekend?” is fine. “Did you finally score with that hot X you were chasing?” is not something that should ever be heard in the office.
When someone tells you something in response, pay attention. “It was great – my son played his first varsity game” can lead to many future conversations. If the other person shares about their favorite sports team, you can ask how they’ve been doing or if that person is excited about the upcoming season without knowing (or caring) anything about the sport. Listening, making sympathetic noises, and remembering key interests will get you far. You get a lot of credit for being friendly from basic good manners.
Do not ever share anything embarrassing or sensitive about another person (“The face lift looks great! Aren’t you glad you did it now that it’s all over?” is not something you share to bolster another staff member who just returned from what others may think was a vacation).
A good listener with good boundaries who does her own job well and helps others is a gem. That’s the kind of a reputation that will help you.
Goal 2: Develop friendships outside of work. It was common during our school years that our “work” environment was also the primary (or sole) source of our friendships. That’s no longer the case. There are lots of ways to develop friendships outside of work (adding friends of friends to our own circles, clubs or meet-ups with common interests, joining teams for informal play of a favorite sport, etc.). I won’t list them all, but again, if you reframe “shy and quiet” as “a great listener” you will go far.
I hope this wasn’t too harsh, but I didn’t want you to make a significant faux pas so early on in a new job.
Best wishes (from an experienced manager who was once “shy and quiet”),