After 15 years, the USDA has rewritten the rules for what must -- and can't -- be served as part of the federally subsidized school lunch program. Whole grains, once encouraged, will be required. Beans and peas, as well as dark greens and red vegetables, will become staples.

Come July 1, chocolate milk will go the way of the deep fat fryer.

But some Bay Area school districts, propelled by a growing healthful food movement and concerns about childhood obesity, plan to go beyond the new guidelines. Oakland's nutrition services director is proposing upgrades to dozens of kitchens and the development of a 44,000-square-foot central facility -- with a 1.5-acre organic farm outside. Richmond High School soon might have a salad bar stocked with produce harvested by students in the garden outside.

Soon, some Hayward schoolchildren might come face to face with "a sushi robot" that specializes in California rolls.

"When we talk about educating our children for life in the 21st century, we have to look at all aspects of what that means," said Rami Muth, superintendent of the Martinez school district, which plans to create an organic gardening and cooking class for junior high school students. "We have to look at helping young people develop patterns in their lives that will support a healthy lifestyle."

More than 70 percent of schoolchildren in Oakland qualify for federally subsidized meals, and many rely on those meals for a large part of their daily sustenance. That number rose, locally and statewide, after the economic downturn. Fifty-seven percent of California's schoolkids are now eligible, up from 51 percent in 2007. That number has grown to 62 percent in Hayward, 42 percent in Alameda County and 38 percent in Contra Costa and Santa Clara counties.

Last week in Oakland, children from Esperanza Elementary and Fred T. Korematsu Discovery Academy lined up for whole-grain corn dogs or vegetarian lasagna. But before they settled down with their compostable trays, many took helpings of jicama -- the vegetable of the week -- and other items from the salad bar, served up by parent volunteers.

The children seated at a table nearby had no complaints. "If you tried this, you would want to eat it every single day," said Adrianna Neal, 10.

Silvia Fong, the lunchroom manager, pays close attention to how much the children leave on their plates. "If they like it, they eat all of it," she said.

She can serve all the spinach she wants, but if it goes untouched, it doesn't matter. Like others in the business of serving food to children, she tries out new recipes and new produce first and encourages the students to take samples. It seems to be working; she says she now serves 20 pounds of greens a day in the salad bar, up from two pounds at the beginning.

In recent years, salad bars have appeared in cafeterias and multipurpose rooms throughout the Bay Area, including all 19 schools in the Oak Grove School District. Nearly two-thirds of the children in the district in South San Jose are eligible for subsidized meals.

Terri Anaya, the district's director of child nutrition services, said its lunches are already close to meeting the new guidelines and eventually will surpass them.

"We intend to exceed it, absolutely!" she said.

Jennifer LeBarre, who heads the Oakland school district's nutrition services department, wants to eliminate prepackaged, highly processed meals from every school lunchroom, hold cooking classes for food service workers and buy at least 25 percent of the produce from local or organic farms. Such changes might not sound revolutionary, but for a department that serves 21,000 lunches daily -- with about $3 each in federal and state funding for labor and ingredients -- it's a significant feat.

Robin Jones, director of Hayward's food services department, has been creative with the district's upgrades. To make the commodity pork taste better, she supplied some schools with inexpensive crockpots. Automatic pasta makers have replaced old fryers. Her department recently opened new cooking kitchens at Ochoa and Winton middle schools, funded entirely from the department's reserves.

Supporters of Oakland's food overhaul, by contrast, are likely to look to the public for help. The physical upgrades included in LeBarre's plan would cost an estimated $26 million, according to a new feasibility study by the Center for Ecoliteracy in Berkeley. It's possible the sum would come from a future construction bond. The Oakland school board is considering whether to place such a measure on the November ballot.

"For me, this is a must-do," Oakland's Deputy Superintendent Vernon Hal said after hearing the presentation. "If our goal is to educate kids, part of educating kids is to make sure they're fed, they're attentive, so they can obtain the skills they need."

Staff writer Joe Rodriguez contributed to this report. Read Katy Murphy's Oakland schools blog at www.IBAbuzz.com/education. Follow her at Twitter.com/katymurphy.