do you ever get that helmet you see the stormcloaks wearing because i joined the stormcloaks but i just got a hide helmet is there a way to get the other one without killing someone?

A certain pickpocketing perk would allow you to swipe it off one.

took one off a stormcloak who died in battle

There's a fort east of Whiterun that has some dead stormcloaks(w/ helmets) lying around.