What’s the traditional symbol for one’s 21st wedding anniversary? Trick question. There isn’t one. Nickel and Brass are contemporary symbols for this celebration. Although maybe not nickel or brass, but certainly metal, these trees at The Public, an interactive art building in West Bromwich, England, suggest a good fill in. I’ll have to remember this place to visit one day. Now I could go off on a tangent about trees and twig art: Or tree bark fashion (floral display): But I think I’ll stick on subject. My husband, Peter, and I our celebrating our 21st wedding anniversary. It’s really hard to believe for it doesn’t seem that long. Now, I…