It really depends on what you consider a house pet. There is some mold (fungi?) growing on the stump of a tree that I cut down a few years back. It seems like it would make a good pet. How much are you offering?

I also have things like:

Stink Bugs.
Grass clippings.
Used motor oil.
Stink Bugs.
Bark.
Very small rocks.

I'm open to offers.