Yeah, I remember thinking a while back it'd be nice to have crib sheets for pony caste abilities and the like, an armour guide, some plant guides and some stuff about wood conjuring and painting would be a good idea. I sometimes forget that not everyone's been fiddling around in the guts of this beast, sorry about that.
Plump helmets should definitely be conjurable, if that doesn't work, try getting a herbalist to collect some surface plants, see if we can't narrow it down the problem.
Unfortunately, most of the new surface plants are just for making dyes and painting wood with, though some are brewable. The update after next will include cocktails and advanced brewing, so a lot of currently boring plants will be valuable for making classy booze, and I'll look into expanding their uses more generally.