Hello, When our grown children were young, we used the Allied Gardens Recreation Center for fun. It has a playground and bathroom facilities. I don't know what the tree situation is anymore since we haven't been there for a while, but it used to have plenty of trees. It is located off of Waring Road on Greenbriar Avenue. Also, in the east county between Santee and Lakeside there is a wonderful park. It is off of Woodside Avenue on Shadow Hill (I think is is Drive). The park is called Shadow Hill Park. It has bathroom facilities (which are cleaned daily) grass, gazebo and nice playground. There is also a basketball court and tennis courts as well as a hiking trail.
Good luck with your precious child.
K. K.