You just might be lucky.
I'm probably lucky too because I received two Faerie Dogmothers from two adventures while still in Chapter 3, and I have also received two Cash Cows as of two adventures ago.
The only thing that I'm not getting is the Desiderium Tree/Sapling. Twice now my Keep dropped a tree/sapling. I collected them but, they just don't appear in my inventory
** I run adventures back-to-back so the chances of getting these rare drops are higher.