These three flags decorate my office: The US and German flags are easy to recognize, but what's the other one for? Glad you asked! It's the local flag of the German region of Baden. It's not a state by itself (anymore), but a region with a long, eventful heritage and, accordingly, a strong sense of pride among the locals.
Now, in general, plastering everything with flags in the US is deemed acceptable. Back home in Germany, I found the opposite to be true: After the Nazi government thoroughly overused flags in every conceivable way, in post-war Germany it commonly results in raised eyebrows when private people put up flags (except during the soccer world cup). However, local flags (be they state flags or regional) are shown off with much more pride and generally accepted as a declaration of heritage.
Of course, in my office, I get to make the rules so I can hoist whatever flags I like :)