Often they are young men dropped off from a truck at the corner with a stack of fruit boxes as tall as they are. Residents quickly pull over or stop in the intersection, hop out and buy a flat of berries and head home, happily thinking strawberry shortcake for dessert.
If the buyers are lucky, those berries are untainted and the shortcake will be a pleasant memory next morning.
But as county health officials warn, you don't know where those berries or other produce came from. Remember E. coli? Don't forget those other not-so friendly pathogens salmonella and botulism. They might be contaminating that produce that looks so appealing, warns Sherman Quinlan, director of environmental health for Contra Costa County.
Instead of shortcake for dessert, the buyers might need intravenous fluids and other antidotes to save their lives and vital organs. Succulent that isn't, but it is what Quinlan and his staff fear each time a street corner operation crops up.
"You don't know where that produce came from," said Quinlan. And if someone is sickened by contaminated produce, health officials are hard-pressed to find the source and shut it down if it's a street corner operation. There is no record of who sold it, where it was grown and harvested and who the wholesaler, if any, was.
Vince Scalise of the Pacific Coast Farmers' Market, which operates the Brentwood Farmers' Market, said many of the street corner vendors carry no identification, making it hard to track their operations.
In fairness to most such vendors, he said they usually buy their supplies from legitimate wholesalers. But the produce just as easily could have been raised in fields contaminated by animal or human waste. Last year, spinach disappeared from produce markets around the nation after at least three people died from E. coli infections brought on by spinach believed contaminated by feral pigs that got into the fields. Commercial spinach growers around the state suffered severe financial losses.
There's quite an array of produce being sold from street corners that can slip by existing health laws, Quinlan said. Unlike vendors at Farmers' Markets who sell only certified produce, as do county-regulated and permitted roadside stands, these street corner vendors can buy their supplies anywhere and sell it un-inspected, he said.
"The county has adopted ordinances related to growers stands, but there are (no health laws) regarding street vendors. I'd love to have one," Quinlan said.
There are zoning laws, agricultural ordinances and traffic laws that can be used to make the vendors move on, but there is nothing to assure the safety of their product, he said.
"We are enforcing the state standards regarding illegal fruit vendors but with our staffing shortage we can't get out as much as we would like," said Quinlan, whose office also oversees inspecting all the county's restaurants.
If the veteran health inspector sounds alarmist, Quinlan feels he needs to be. He recalls the lysteria-contaminated soft cheese being sold door-to-door in some neighborhoods. Lysteria can cause spontaneous abortions in pregnant women and could even be life-threatening to adults, he said.
"The public has employed us to enforce the state standards. It is state law that the food be protected. The only foods allowed to be sold in open are whole, uncut produce and eggs in shells," he said.
County Supervisor Mary Piepho of Discovery Bay and Agriculture Commissioner Edward Meyer both agreed these vendors are unfair competitors.
Meyer's office enforces the regulations governing roadside stands and Farmers' Markets, which detail how the stands will be built and operated as well as what can be sold there. Most roadside stands, depending on their size, must apply for an operating permit. The operators must provide parking space.
Street corner vendors, except in a very few cities, don't need permits, parking spaces and need only the space they stand on with their boxes, he said.
Piepho wants this changed. She said she's already asked Sheriff Warren Rupf and the health department for options on how to prevent illegal vendors.
"The Sheriff and Commissioner Meyer tell me they do have recourse against the vendors. If the public calls the sheriff when they see a street corner vendor, a deputy will come out and shut him down. That's what has to happen. He (the vendor) may go around and spread disease around the county and that's unacceptable" she said.
"I've seen women (vendors) with umbrellas and boxes of produce standing alone. It becomes a public safety issue for that person. They are collecting cash and there are those who would take advantage of that."
"It's really a very risky situation for everybody," added Piepho. "The public is at risk and the vendor is at risk. It hurts the local farming community in the pocketbook. My office is working very hard on supporting farmers with policies to encourage them to cultivate, process and market their food, and then somebody comes in with a couple of boxes and right away they're in competition."