What Means Switch - Questions

My question regarding the reading :

What, if anything, does their front yard signify? The fact that people are also mowing over their plants, even Sherman's parents ran over a small tree. And what about their building a wall?

I responded to Robbie's question:

Why does the author spend so much time talking about Sherman Matsumoto? Why is it significant that we know about him?

The author spends time talking about Sherman Matsumoto because he is an importnant character that represents the Japanese culture our main character is exposed to. It also shows what the Americans in their school know about Oriental culture, they can't tell the Chinese from the Japanese. Even she dosen't seem to recognize the difference on the level her mother does (ie. kicking him out of the house). He is the only Japanese boy she knows, and she falls in love with him. Showing their relationship helps the reader understand the personality and thought process of the girl. We know her better through what we see in her relationship.