The Kindergarten Cop's kid is going back to school.

Yes, that was Arnold Schwarzenegger's ex- housekeeper/ baby's mother Mildred Baena, and their son Joseph, shopping at an Office Depot in Southern California in this photo just released to RadarOnline.com.

Mildred -- who worked for Schwarzenegger and Maria Shriver at their mansion in the posh Brentwood neighborhood of Los Angeles for 20 years -- wore a pink and white striped shirt for the Saturday shopping trip. Joseph, 13, sported a shaggy 'do reminiscent of his dad’s Pumping Iron days. He wore a plaid short sleeve shirt and shorts, carrying a blue backpack.

Arnold Schwarzenegger’s baby mama Mildred Baena is finally coming forward with her side of the story, more than a month after it was revealed that he fathered a child out-of-wedlock with the former housekeeper.

According to Baena, their son, now 13-years-old, found out just one year ago from his grandmother that the former governor was his father to which he responded, “Cool!”

In what Baena claims will be her first and only interview, she opens up to HELLO! Magazine about the intimate times she shared with Schwarzenegger saying it was only “a few times.”

As Alanis Morrisette would say, "Isn't it ironic?"

PHOTOS: Arnold Rides Mildred Avenue

His life in shambles after his affair/ lovechild with ex-housekeeper Mildred Patricia Baena was exposed last month, Arnold Schwarzenegger was snapped crusing down Mildred Avenue in Venice Beach Sunday.

If Maria Shriver only knew, she probably wouldn't have been smiling.

We've obtained another photo, this time of Shriver and her former housekeeper Mildred Patricia Baena, before anyone had any idea they had so much in common. (They were both pregnant -- at the same time -- by Arnold Schwarzenegger.)PHOTOS: Arnold Schwarzenegger & Maria Shriver Through The Years

Also in the pic is Maria's brother, activist Anthony Kennedy Shriver.

RadarOnline.com has obtained this just-released photo from a 2001 party attended by Mildred Patricia Baena and Arnold Schwarzenegger, a decade before anyone had any inkling they were looking at a pair of parents.

The pic was snapped at a party to celebrate Baena's niece's Quinceañera, a coming-of-age party in Latino culture for girls turning 15.

PHOTOS: Arnold Schwarzenegger & Maria Shriver Through The Years

Mildred Baena, Arnold Schwarzenegger's one-time mistress, filed for divorce from her husband in 2008, and in the exclusive documents obtained by RadarOnline.com, she said she did NOT have any children with her husband!

EXCLUSIVE DOCS: Mildred Baena's Divorce Papers

The man, Rogelio de Jesus Baena, is listed as her son's father on the child's birth certificate, but the child's real father is Arnold Schwarzenegger.

Mildred Baena, the mistress of Arnold Schwarzenegger and mother of his illegitimate thirteen-year-old son, has gone into hiding.

Baena, known to friends as Patty, was last spotted at her upscale Bakersfield, CA home Sunday, leaving out just days before the news of her scandalous affair with the former California  governor broke.

PHOTOS:  Arnold & Maria Through The Years

The mother of Arnold Schwarzenegger's love child threatened to go public with sordid details of their illicit affair -- all because the Governator TERMINATED her employment.

A blockbuster RadarOnline.com and Star Magazine joint investigation has uncovered the real reason behind the former California's governor's admission that he fathered a son out of wedlock -- it was because a shameful Schwarzenegger fired his mistress from her job as a housekeeper in a desperate attempt to save his marriage to wife Maria Shriver.