DUDE, if your mother have a green card, you can apply for one too as her immediate relative. You would be stupid not to! However, if still are a foreign citizen, then you need to get an
F-1 visa through your school. YES, you are an international student. But, you should seriously apply for a green card through your mum once you get into the country. It may take some time though, but eventually if all goes well you will get it.