Lol your answer is on the page you linked. "The grass is the one from IT... I.T/I.W/KITO has it." Since I have an impressive title server downloaded, I'll see if I can upload it for you.
EDIT: Alright, done. The download link is here:
http://www.mediafire.com/download/5ws5k2vgzibyskr/IT_Grass_Pack.zipI renamed the grass textured you wanted to ITGrass since there was already a grass file in FH. I also included a yellow and snowy grass just in case you wanted those too. Just dump all the files in the my objects folder, start up FH and they should be in their own separate item category in the map maker.