My current favourite veggie for breakfast is Brussel Sprouts, something I used to hate as a kid!! I roast up a large tray of sprouts, butternut squash and red onion, and eat with whatever protein I have available. It's so good, so easy and handy to prep ahead for a few days' breakfasts. I've used frozen sprouts & squash too so I've often got the ingredients in the freezer.
Just don't bring it in to the office and microwave them or you'll stink the office out ;)
Other than that I find a veggie packed omelette/fritatta great for getting in the veg, dice up everything small add in potato, bacon etc and you won't really feel like you're eating a plate of veggies for breakfast!