Theressa came up with a nifty method for finding trees of interest. Portland's Urban Forestry division maintains an online list of Heritage Trees of Portland. Heritage Trees have lived a long time and attained such majestic heights that someone nominated them and a committee accepted them for special recognition and protection. Besides inspiring awe, huge trees presumably give relatively huge yields of whatever seeds, nuts, fruits, or whatever they normally produce. So Theressa started looking through the lists for species which make human-edible products, and we've already started visiting some of the trees. Species of interest to us include: oaks, elms, beeches, monkey puzzles, chestnuts, hickories, pecan, butternut, ginkgo, and pines.
Similarly, Theressa found maps and tree listings for various tree walks (see bottom left of link) around Portland. She also discovered that when we participated in the Neighborhood Tree Liason program, we were given some tree walk maps not yet available online.
Although the public must have visual access to a Heritage Tree, the public does not necessarily have harvesting access. If Theressa and I get organized enough, we'll start adding some of the harvestable edible trees to the maps at Urban Edibles. Since I don't know how soon (if ever!) we'll get around to that, I thought I'd at least share those resources for people in Portland who may want to use them, and to jog other people's creativity in finding local resources of their own which may shortcut their way to finding interesting trees. Enjoy!