I have some wood which may be walnut that was used for cribbing timbers for the covered bridge in New Berlin, PA. It was built in 1878 and demolished in 1936. I do not have a certificate. I got the wood from a civil engineer in New Berlin.
You can see a pen made from this wood on my FB page - Timber Creek Turnings
Darrell, I have some wood from a covered bridge in Paris, Missouri. You can see some photos of the bridge on my web site. It does have a COA. PM me if interested.