I keep finding that yellow poppies are turning up in my followers' inventories. Even Thorvald's when he was briefly with me.

At first I wondered whether some horrible glitch was turning items into poppies. (Savegame corruption; my having forgotten to install the Unofficial Patch and decided to forge ahead regardless; whatever.) However, I've found a couple of remarks to the effect that Vollinger in particular (not a member of my party) simply loves poppies: This leads me to suspect that something deep in the follower A.I. code likes, every once in a while, to pause and pick poppies, thereafter to carry them all around the world of Arcanum. But perhaps it's just the followers in my play-through who've decided that they're a band of brothers united by the sign of the yellow flower...?

I think the yellow poppies are ingredients for one or more herbalism recipes. So I guess followers are coded to grab them.

Well, yes, but mine seem to value poppies in particular (even though there's not a single herbalist in my merry band). Perhaps other people have found themselves leading the Kadura Stem Fraternity or the Ginka Root Gang, but my lot insist on having one or two poppies apiece.

NPCs in Arcanum pretty much want to pick up any item off the ground all of the time, not just poppies.

Principally plants and (some) dropped items, in my experience. My party likes picking flowers and tidying up after me, but I've just taken them to a certain ogre's cave, and they showed no interest in the items on the ground there. Not even the money.

Sometimes this can be an annoying feature. If I want something dropped, I want it gone. However, when some enemies cause weapons to fall out of your companions' hands, this is a god send. Only once did it provide an interesting event. My character shamelessly threw a Tarant newspaper to the ground in front of a Paper Boy. The vendor, with pride in the product he sells no doubt, picked it up without complaint. What civility the man showed with the poor position he held in society! And me, of all people, strutting my smoking jacket and highfalutin talk, showed no society like a depraved Orc.

Your followers are obviously suffering from some sort of existential crisis.*

The only known solution is the liberal application of a bottle of Yukon Jack, which should at the very least make Sogg and Sebastian quite happy.

*If you don't want to watch the whole thing, skip ahead to around 3:30; for some reason, the timestamp tag isn't working properly here.