One of them, shiny and scrubbed, shares a hallway and a bathroom with an Englewood Starbucks. Another, in a historic stretch of northwest Denver, has mismatched china and a certain coziness. At the third, on a gritty stretch of East Colfax in Denver, you might see a diner finish a meal and then start cleaning windows.

All three are restaurants, but it’s not the food that sets them apart.

It’s their ideals.

Thanksgiving comes once a year for most of us, but the holiday’s spirit — embrace generosity, give thanks — is the very foundation of each of these restaurants, where all can sit down and eat, even if their wallets are empty.

The three nonprofit restaurants — two opened this year — depend on the generosity of diners who are willing to pay a little more to cover the bowls of stew and plates of eggs of fellow patrons who can pay only a little or nothing.

“We have found $100 bills in the donation box,” said Cathy Matthews, 45, one of the founders of Cafe 180, which opened at the end of July. “One person came in with a box of pennies. It’s not the amount that matters.”

The average diner at Cafe 180 pays $8 to $9.

To thank the community for supporting her business, Matthews today is offering a full Thanksgiving repast to those who walk in — free of charge. She is planning on serving as many as 200 diners.

The region’s other pay-what-you- can places — the Comfort Cafe in northwest Denver, which opened last summer, and the 4-year-old SAME Cafe on East Colfax Avenue — have the same business strategy as Cafe 180. As a result, those who can’t usually afford to eat at restaurants now can, even if all they have is a handful of change or a willingness to wash dishes.

The pay-what-you-can movement, which started in 2003 at One World Cafe in Salt Lake City, hasn’t exactly captivated the nation; there are only about 10 such places in the country. Three of them, though, are in the Denver area; no other metro region supports as many.

More coming to the table

Most of these eateries are small-scale affairs, but that is changing.

The national Panera Bread chain opened a pay-what-you-can restaurant this year in St. Louis, where the company is based, and aims to open at least two more around the country within the year.

Panera Bread’s founder heard about Denver’s SAME Cafe, said company spokeswoman Kate Antonacci, and he wanted Panera to do something similar to help people in need.

“We’ve had people come in from all over the map,” said Antonacci. “They will come in for a cup of coffee and leave $20. We have families who come in and say they haven’t gone out to a meal in months and they don’t know where their next meal is coming from.”

One of the things Cafe 180’s Matthews likes about this approach to running a restaurant is how it brings together people who might otherwise never spend time in the same room. At soup kitchens, for example, the only people eating are the down-and-out.

Matthews, who long has given generously to charity, decided about a year ago she was too distant from the people she was helping through her donations.

“My view of the world was too narrow,” she says.

Like the Panera Bread founder, she visited the SAME Cafe, Denver’s first of these restaurants, and left with the conviction to start something similar, only in Englewood, where she lives.

Months later, she had a lease on a former Spicy Pickle and a head cook, Dirk Holmberg, who had worked at restaurants around the city until alcoholism left him homeless and desperate. Four years ago, he stopped drinking. Now he runs the Cafe 180 kitchen.

The restaurant “isn’t a handout, but a hand up,” said Holmberg, taking a break before a lunch rush. “Through volunteering, you develop self-esteem; you are encouraged to say, ‘Yes, I can do something.’ “

Volunteering figures into all of the Denver restaurants. At the Comfort Cafe in northwest Denver, a cozy, historic place with art on the walls, Carmen Petersen, who describes herself as a “senior citizen,” trades her voice for food if she’s coming up short.

“I’ll sing them a little song,” said Petersen, dressed in a skirt and fancy hat. She spends most of her free time singing in choirs, nursing homes, wherever her voice is welcome. She also volunteers at Comfort Cafe. Most days, she stops by for a meal.

“Every day is gourmet to me,” she said.

Across the room from Petersen, Sarah Roman, 33, and her friend Korina Keating, 30, played peekaboo with their 2-year-olds while they munched on offerings from the restaurant’s long menu.

“I came because I was curious about the concept,” Roman said. “I like the idea that if I pay a little bit more for good food, it helps somebody else.”

For her quiche, fruit salad, green salad and beverages, she paid $12. Son Silas, in a high chair, consumed most of it.

The economics of altruism

The model is of interest to economists, especially those who study intersections of human behavior and commerce. Classic economics presumes a measure of “homo economicus” — the idea that people make economic decisions out of pure self-interest — but restaurants such as these complicate matters.

Pay-what-you-can restaurants survive through “a mixture of shame and altruism,” said Philip Graves, an economics professor at the University of Colorado. “I think people do care for other people, and they would be shamed if they didn’t pay a fair amount.”

He added: “There’s a lot of evidence that people have a strong sense of fairness, and nobody knows why that is. It may be genetic.”

Of particular interest to Graves is how the restaurants collect payment. If cash exchanges occur with employees while other diners are within sight of the transactions, he suspects giving would be higher than if diners anonymously slipped money into a drop box.

Among the Denver outposts, cash- collection procedures are a mix. Cafe 180 and SAME Cafe use boxes; at Comfort Cafe, diners hand money to a cashier. For now, at least, all the models are working. Whether they become community institutions remains to be seen, but they have hope: One World Cafe in Salt Lake City has been operating for nearly eight years.

Restaurants around the country are experimenting with different approaches to pay-what-you-can, said Denise Cerreta, the founder of the One World Everybody Eats Foundation in Salt Lake City who also opened the first pay-what-you-can restaurant there.

At this point, she is receiving up to five e-mails a week from entrepreneurs around the country who want to start similar cafes in their towns.

“When I first started this, I got heckled,” she said. “But now people are saying, ‘Wow, this really can work.’ There are options other than money for people to eat together in one place.”

Douglas Brown: 303-954-1395 or djbrown@denverpost.com

Pull up a chair

Three restaurants in the Denver area operate on a pay-what-you-can basis:

Cafe 180, 3315 S. Broadway, 303-761-4510, www.appetitesunite.org. Tue.- Sat., 11 a.m. to 2 p.m.

Comfort Cafe, 3945 Tennyson St., 303-728-9251, thecomfortcafe.net. Wed.-Sun., 7:30 a.m. to 2:30 p.m.

SAME Cafe, 2023 E. Colfax Ave., 720-530-6853, soallmayeat.org. Mon.-Sat., 11 a.m. to 2 p.m.