I can confirm I have all the same maps as Parrottmath, they were just there when I did the steam install, I haven't copied anything over whatsoever. I've been using these maps all beta-long, especially the wildlands map, which is my favourite. When I start a new game there is an option to load all these maps on the setup screen instead of a random map.
They are not located in the my documents folder, steam has put them in the program directory. The path for me is:
C:\Program Files (x86)\Steam\steamapps\common\FE Legendary Heroes\data\Maps
Edit: Also, I hope you take Parrottmath up on his offer to use his map fixes, as the broken river tiles can be quite irritating.