Arts & Crafts Old Oak Chair with side table

We inherited this chair and the little side table with our 1920s cabin in Northern California, and I'm wondering what it might be worth. What do the spade designs mean? 

It's oak for sure, and looks to have been re-upholstered at some point (a couple of brass rivets are missing). The chair has no nails that I can see, but only dowel type construction. 

Fair