What a find! I remodeled a kitchen in the Wedgwood area of Seattle, and when I started taking the old cabinets apart the first piece split from one end to the other, and I knew it wasn't plywood. They were solid fir boards, up to 21" wide. Destined to become a nice art box. I'm still getting up the nerve to go at the dovetails.
Just out of the wild, before its first its first shave.