Straw Man

The term "straw man" in common US English has a much more complicated meaning than what I think you are trying to use. Straw man is used whenever you are debating someone and they misrepresent what you said and then refute the misrepresentation of your argument. You would say that they are attacking a straw man. Visually, it implies that they are making a person out of straw to fight instead of fighting something real. The term "straw man" could also imply that a person is merely taking up space in a position, but doesn't do anything of importance. The more common term for what you are saying is "Scarecrow".

When I was a child, my mother usually took would take my sister and me to visit my maternal aunt. My aunt has been living lives in a the country, where is 50 km from my city.

At that time, to go When we went there, we had would have (When you use "had", it is correct, but it makes it sound like it just happened one time in the past. To make it sound natural and imply that it was a common occurrence in the past, use "would have") to catch a bus. Then, because my aunt's house was surrounded by rice fields and was far way from the bus station, we had would have to walk on a small street long for many (or "for several") hours. On the street to her home, people would often put some straw men at the corner of their farms. 

A straw man is made from straw and nylon bags. Its shape is similar to a man standing, even except this man could can not move. To be honest, at the first time when I saw it, I was very scared.

One time, while going on foot walking to her house, I asked my mother what the scarecrows were for about the meaning of hanging the straw men. She explained them to me. Since then, I have known  know that farmers have done do this to keep birds from eating some grains of rice. Use present tense (do this) in this instance, because the farmers are still doing this today, and you still have the knowledge today.

Today, many farms have been destroyed and then to build built factories, buildings..etc.. Therefore, children rarely look at see the straw men like that as I ever did.