So with the new unstable branch the plant lover trait was released. Anyone with plant lover will always be super happy o.o I have hearthlings with +8 stacks from the plant lover alone D: intended or a bit too strong? 
I think we’re tuning that now. Some of the new traits included in this last unstable have issues, we fixed them but they didn’t get into the build. Sorry!
Could you specify when you’re seeing those hearthlings with 8 stacks?
Are they farmers, or just workers?
This specific one I’ve noticed is a trapper. Seems to get it when he eats.