Pinecones are fun for gerbils and cheap to free for you to get for them. If you pick up the pinecone in the yard, make sure it had not been sprayed with poison. Some pinecones are wet. Let it stand to dry then microwave it for 25-40 seconds on high. Microwaving will kill any mites or other parasites it might be carrying.
Guinea Pig Dress Cookie Monster and Pom Poms! (stock B)
In the high plains of South Dakota, USA