I love Marin in September. The mornings slowly get darker and the air crisper, but the afternoons are still warm. Late summer fruits and vegetables are also at their peak and their fall successors are getting ready to be harvested — just look at the grapes I spotted in my neighbor’s front yard on a recent walk! (It was so hard not to take one and try it. I didn’t. I couldn’t.) After admiring my neighbor’s gorgeous grapes, a couple more minutes into my walk, I saw a plum tree growing on the side of the road. This is the main road that leads to downtown. The tree was full of plums, and this time I couldn’t resist the urge to taste one. The tree was so full of fruit that the branches were hanging a bit low. This tree wasn’t planted in anyone’s yard, it was planted outside a fence on a hill that seemed like public land, at least that’s what I hoped! So I ignored the cars driving past me and what …