Grassy Areas

I have a feature to add to OSM, grassy areas, or at least the ability to change the language from British English to American English.
sometimes, in parking lots, they have areas of grass, and if that is what the meadow is for, let me know. But sort of on that same note, could you add american english as a language option. I would like an american term to call the highways and main roads in my area, especial since there could be debate as to whether or not they’re actually motorways.

Also in that area, there is the chena floodplain, which is used to move water from the Chena River to the Tanana River, when the reiver gets too high, please add floodplain as an area.

As RV’s are big here in the US, could you add dump stations as well? A dump station is where RV’s can empty their grey and black water tanks. grey and black water is the water from the sinks and toilet respectively.
good image for dump station: http://www.trafficsign.us/650/guide/d9-12.gif