Facebook's online garage sale groups can help you trade your stash for cash.

For Linsey Skolds, starting over after a divorce meant getting rid of more than a marriage. She bought a smaller house for herself and her children, and she wanted to move into her fresh, new life without all the baggage from the old one.

Skolds was an experienced eBay seller, but now she had a lot more to sell and little time before her move-in date. So she began advertising items in her local Facebook “For Sale” group. It was simple: snap a picture, name a price and post. The first few items sold quickly. She posted more.

Soon, she says, “I had quite the following. People were waiting every day for my posts.” She sold everything from dishtowels to furniture. Buyers would collect their purchases from her porch and leave the payment in a designated hiding place. “I was going to the bank every night because I had so much cash,” she says. “It went on for weeks.”

It wasn't easy. “I remember backing out of the driveway and thinking, ‘I can't believe I sold all that stuff.'” But it was freeing. And there was a welcome bonus for this former stay-at-home mom who was headed back to work: She earned about $15,000. It was enough to pay for the move, buy new beds for herself and her daughters and redo the bathroom in her new home.

The site where Skolds held her sell-off is open only to residents of the 43209 ZIP code (Bexley, Berwick and Eastmoor). With about 4,200 members, it's one of dozens of local garage sale groups on Facebook. Memberships range from a few hundred to tens of thousands. Nationally, so many people are buying and selling on the social media site that in 2016 the company initiated Facebook Marketplace to monetize the activity for itself.

But some users prefer to stay within their smaller neighborhood groups. While many e-commerce sites exist for those who want to buy and sell used goods to a mass audience—Craigslist and eBay, for instance, as well as specialty sites like ThredUP and PoshMark for clothing—the success of the Facebook groups springs from the trust that comes from dealing only with neighbors. Administrators eject members who rack up complaints for offenses like reneging on a deal, failing to show or false advertising.

Ilana Eidelberg Spector and a friend started the 43209 “For Sale” group five years ago. In the early days, there was some drama as the rules evolved (no price-gouging, no firearms and buyer beware: If you purchase something and don't discover it's broken until a year later, you're on your own). But today she spends about 30 minutes a week on her role. “I've had enough people tell me that they love the site that it's still worth doing,” she says.

There may be a social benefit to the groups. Skolds says she met some new people, and it made her feel good to get her things in the hands of people who wanted them. Sometimes people still recognize her in the neighborhood and mention an item they purchased. “It was a really good experience,” she says.