In order to answer correctly, we need to know if you lived with your mother (except for temporary absences such as atttending school).
Also, did you pay for more than one half of all the money that was spent to support you last year?
Where did your son live last year? If more than one location how much time in each?
Thanks for the information.
Since you (or your child) did not live with your mother for more than one half of the year neither you or your son can be claimed as a qualifying child of your mother.
A qualifying child must have the same principal residence as the taxpayer for more than half the tax year. See http://www.irs.gov/newsroom/article/0,,id=133298,00.html fro more information.
You and your son are also not able to be claimed by your mother as a qualifying relative. You because you provided more than one half of your support. Your son, because he is your qualifying child and so only if you do not need to file a return could your mother claim your son as a qualifying relative.
Sorry, your mother can not claim you as a dependent.
I hope this helps, even if it not the answer you would prefer.