About 20 years ago I purchased 2 black walnut trees. When they arrived they were only close to 2 feet in height. I planted them but they both died. Many years later I notice a tree growing in my neighbor's back yard. This tree had a fruit on it that looked like a kiwi. It has a musk-like odor. The squirrels love this tree and strips this tree of all of its' fruit. I looked up on the internet and it seems that this is a black walnut tree growing in my neighbor's yard. I live in a semi-attached home and this tree is located 3 feet away from where the original 2 trees were planted. My neighbor is mystified as to where the tree came from, and 80% of the tree branches are in my yard while the actual tree trunk is in my neighbor's yard. My neighbor won't prune the tree and one of its' branches damaged the roof of my home. While I'm glad to see the tree tried to save itself by producing a new tree I wish that it didn't grow in my neighbor's yard. Have you ever heard of walnut trees reproducing themselves after they died? Years ago I use to feed the squirrels walnuts and peanuts, could it be that the tree grew from a squirrel who buried the walnut in the ground? Thank you in advance for your kind attention to my question.