This was an informative and fun exercise last year when I tried it. It gives you that feeling of doing something effective and tangible, you know? Something that will deliver benefits to the residents and the wildlife over the years. You can sign up to discuss planting locations at one meeting: https://mysticriver.org/calendar/2018/4/12/planting-trees-in-somerville-public-meeting
And/or you can participate in the planting itself when they get the trees by signing up here: https://mysticriver.org/calendar/2018/3/29/plant-trees-in-somerville