“Oh boy,” a woman proclaims as she approaches a stand at the first National Heirloom Exposition in Santa Rosa, California. “Free seeds! How fun is this?”

She is not the only one excited by the exposition, an event co-organized by the Petaluma Seed Bank in nearby Petaluma.

Attendees are amazed by towering stacks of pumpkins and gourds that rise nearly 5 meters (16 feet) into the air. People taste little-known varieties of fruits and vegetables at one of the exposition’s 250 vendor booths and exhibitor stands. And more than 70 speakers fire up the crowd about heirloom produce. The speakers include Paul Blundell of the Southern Exposure Seed Exchange and celebrity chef Alice Waters, owner of the famed restaurant Chez Panisse.

Heirloom plants are varieties cultivated by early farmers. Most heirloom varieties are open-pollinated, meaning they are naturally pollinated by wind, insects, or birds.

Jere Gettle, owner of the Petaluma Seed Bank, says there is one simple reason for putting on the three-day event: “The overall thing is to bring everyone together around the produce,” he says.

At a booth nearby, Patrick O’Connor and Mat Rogers of Berkeley, California, discuss the importance of getting seeds into the community. O’Connor is a volunteer at the Bay Area Seed Interchange Library (BASIL), and Rogers is the director of Agrariana, a nonprofit organization focused on urban agriculture and sustainability.

“I think the whole point is to come to realize that there is not only one type of tomato,” Rogers says.

As if on cue, Ursula Silva, a neighborhood gardener from Livermore, California, wanders over to the booth with a bag full of more than 70 varieties of tomato seeds. “I’m actually looking for more heat-tolerant tomato seeds,” she says.

O’Connor and Rogers suggest she visit a booth helmed by Native Seeds/SEARCH, a nonprofit organization from Tucson, Arizona. Native Seeds/SEARCH preserves and distributes seeds for plants that grow in the arid Southwest.

Organizers estimate the mid-September event drew more than 10,000 people. Visitors came from as far away as Hawaii, Maine, and Canada.

“Everyone is asking,” Gettle says, “is it going to happen next year?”