On the west side of busy North Stone Avenue is a mailbox that's probably caught your eye as you rode by. It's a dark brown metal color, wrapped by huge flowers and leaves.
(Though I'd spotted this place before, I finally took the photos on May 20th — by riding my bike along narrow Stone Avenue early in the morning, before there was much traffic. Bike lanes here are tiny, and there are no parallel side streets along this part of Stone.)
There's lots more iron work around the home. See the page 3645 North Stone on TucsonArt.info.