It used to be enough to know where your food comes from. Now, seeing is believing — especially if the view is from a dinner table set up among the rows of beets and carrots.

In agriculture-rich Ventura County, several farms and some of the restaurants that use their produce are teaming up to offer tours and in-the-field dinners designed to feed, educate and entertain visitors.

“We realized when we opened last year that some people don’t care where it’s coming from; they just want food that tastes good and is healthy. But when you’re in Ventura and surrounded by all of this great stuff, you have to make use of it,” said Rachel Main, chef and co-owner of Main Course California.

Once the farm manager for Thomas Keller’s storied French Laundry restaurant in Napa Valley, Main now is planning tours of area farms and ranches that supply her Ventura bistro with its vegetables, poultry and beef.

But first comes the “all local dinner tasting” she and sous chef Nadia Licea plan to prepare tonight from ingredients that traveled no more than 100 miles to reach the kitchen: pasture-fed beef from Watkins Cattle Co. of Ojai, pistachios from Maricopa and citrus, strawberries and leafy greens from Santa Paula grower Dave Pommer.

Main also is one of six chefs participating in a local-foods lunch that will be served on April 17 as part of a farm-tour fundraiser in Ojai. Proceeds will benefit BRAVO!, a children’s education program connected to the Ojai Music Festival.

Perhaps as an indication of the growing interest in farms and farming, the tour already is sold out, said Alice de Dadelsen Asquith of the Ojai Festival Women’s Committee and a co-owner of Ojai Olive Oil, one of the stops on the tour.

But additional tickets for the lunch have been made available so that more people can get a taste of what is being produced in the area, she added. (Reservations, $35, are required by April 15; call 646-2094, ext. 100.)

Also taking part in the lunch: organic vegetables donated to the cause by John Fonteyn and Elizabeth Del Nagro of Rio Gozo Farm, which grows carrots, kale and French breakfast radishes for delivery to community supported agriculture program members in Ventura.

Located on 4 acres of what used to be the Ojai Honor Farm off Baldwin Road, the site is an example of the farm-dinner trend at its most gritty and most glamorous.

Next month, it will be the setting for a white-napkins-and-tablecloths event staged by Outstanding in the Field, a Portland-based outfit that travels from farm to farm in a red-and-white, 1953 Flxible transit bus loaded with silverware, a serving staff and portable kitchen equipment. The bus also is packed with enough folding chairs to seat more than 120 people at the single, communal table erected at each host location.

During the May 29 dinner at Rio Gozo Farm, guests will sample wines made by Ventura vintner Michael Meagher of Vino V and taste dishes created by Tim Kilcoyne, chef and owner of The SideCar Restaurant in Ventura — all while sitting within reach of vegetables growing in the slightly sandy, terra cotta-hued earth.

Despite the $200-per-person price, tickets for the dinner sold out the same day they were released.

Kilcoyne, who also was the featured chef when Outstanding in the Field presented a dinner last June at McGrath Family Farm in Camarillo, wasn’t surprised by the response. Among the guests for that dinner, he said, was a family of three who flew in from Japan to attend.

Contrast that to the free, and freewheeling, every-month-or-so farm dinners that Fonteyn and Del Nagro put together for volunteer harvesters and members of their CSA program.

“The main difference is the dress code and the cost,” Fonteyn said, laughing. “Basically, if you work, you eat. You can’t retire on our pay, but you don’t go hungry.”

Nor is it likely that you’ll have any complaints about the food, which tends to follow Fonteyn’s general rule of pairing in-season “roots, shoots and fruits” — like roasted beets with fresh dill and tangerines — in a single dish.

“John and I like to cook and my dad is a professional chef,” said Del Nagro, whose father, David Del Nagro, worked at The Oaks and The Ranch House before retiring. “The food John makes is gorgeous and could not be more fresh; it’s like a new kind of fine-dining.”

But the homegrown farm dinners are about more than encouraging free labor, Fonteyn said.

“The people who come and help have a real connection to where their food came from that week; that’s what I’m after,” he said.

While many of Rio Gozo Farm’s volunteers come from Ojai and Ventura, others are WWOOFers — travelers who use an organization and Web site called World Wide Opportunities on Organic Farms to connect with farmers in need of temporary help, Fonteyn said. Payment may come in the form of food, accommodation and/or hands-on experience with organic farming practices, according to the site.

Fonteyn and Del Nagro will need to rely on volunteers more than ever this month, when they’ll be honeymooning in Puerto Rico.

They’ve known each other for about a decade but didn’t begin dating until about a year and a half ago, when, Del Nagro jokes, she angled for an invitation to one of Fonteyn’s renown farm dinners.

Their wedding will take place Saturday at another Ojai-area farm that was the setting for a previous Outstanding in the Field event.

“We are very comfortable with Bohemian elegance, with being as dirty as we are fancy,” Del Nagro said with a laugh.