That'd be any headgear not dropped by an MvP. The donation page doesn't list all of these, but it does list all the ones that are dropped by MvPs and thus you can simply check this list. If the headgear is not in this list (and it isn't something you see in any other lists, such as kahos which cost more or valk helm which cannot be donated for) then it's safe to assume it's a non-MvP headgear. Most headgears you make through a quest will be non-MvP headgears, and anything you can't get by a quest or by monsters dropping them (e.g. Kawaii ribbon) is probably a non-MvP headgear.
The list of non-MvP headgears is pretty long, which is why it isn't on there. If you see a headgear in game that you want but don't know what it's called, you could ask the wearer or search rms for it. I believe someone posted a comprehensive list of all existing headgears (I'm not sure if all of those exist on our server, but most would anyways) but I don't remember where that list is. I have it saved somewhere on my hard drive though, and if you want it I can send it to you.
