You can try making them yourself if you are feeling dedicated. The blog has a cool article on map art http://empireminecraft.com/blog/tips-and-tricks/design/782-guide-to-minecraft-map-art/#more-782
Wow. I seriously thought you had just photoshopped that onto an image. The original image hid what it was placed on making it look fake. Also, great job.
They also shouldn't be in a place near the wild spawn or something. Flags shouldn't be easily griefed, obviously. Also, on the subject of flags... I'd really love a Frisian flag, but I don't think there are many Frisians on EMC.
Well... I don't live in Friesland but my family does originate from there. It were my grandparents who decided to move from Friesland to the "Randstad", so yah. I suppose that makes me a 2nd generation Fries (sort off)