Paul Walker's Mom Files for Divorce

Paul Walker's mom has pulled the trigger on her 30-year marriage ... filing for divorce.

In the docs -- obtained by TMZ -- Cheryl Walker cites she's been separated from Paul Walker III for almost 12 years.

Sources connected with the couple tell us her decision to file has nothing to do with her son's death last year.

We're told they had a very bad, tumultuous marriage and the separation was anything but amicable.

Cheryl is asking for spousal support.

In terms of assets ... she listed a gun collection and a house.