Was just wondering who wore the white helmet covers? Was it certain roles like support gunners and mortar crews or just people who were issued them?
And where can you get them and how much are they?
Don't worry, Wikipedia knows all, it states that soldiers made the white helmet covers for camoflauge.
Tear up a white bed sheet. 
Dawson; Baker Company; 101st Airborne; 82nd Airborne; 5th Rangers, 89th Panzer Stählern Füchse, 6th FJR.
Yea Dawson is right, troops tore up old bed sheets for not only helmet camo but also to camoflage their torsos. I dont think it was anyone in particular who did it, just an opportunist thing if they were in snowy places for prolonged periods of time.
to my knowledge they were field made, however you can buy "reproductions" at this website:
http://serviceofsupply.com/ReproFieldGearEquipment.htm
Looks good, although I prefer the more un-taylored "material shoved in where it fits" look, that cover looks to be taylored much like the USMC helmet cover, and doesnt break the outline of the helmet much
