Reporter Rachel Dubrovin tells us where you can find them, and check out a book for yourself.
"It's just a fun talking point," said Moscow Parent Jesica Sweedler DeHart.
It's an international trend that's been gaining popularity since 2009.
"We have a Little Free Library," said Sweedler.
"We have a lot of books in here," said Second Grader Asher DeHart.
"Mysteries… dictionaries," said Fourth Grader Emmet DeHart.
"Easy readers..." said Asher DeHart.
"We have neighbors, all around the community, that stop by and put in books and take books and it's just a little library," said Moscow Parent Julene Ewart.
So here's how it works. You can walk up to any of these Little Free Libraries, like the one here on Polk Street… Open it up… See if there's anything interesting that you might want to take… Or you can simply leave a book… And then just walk away."
"We had a few kids say, 'Really? We can take them for free?' said Ewart. "We're like ya, no money."
Julene Ewert and her son Ian Schlater installed theirs about a year ago.
"What I like about it is because you can wake up every morning and expect something new," said Palouse Prairie Charter School Fourth Grader Ian Schlater.
Jessica Sweedler DeHart said that inspired her to put up her own library here on Monroe Street near East City Park.
"I think it's really important to think of reading as being a write, not a privilege, and access to book as a right not a privilege," said Sweedler DeHart.
Now, there's at least five of these libraries in Moscow. We found this one on Veatch Street. Some of them are registered on Little-Free-Library-dot-org, the official website that maps out thousands of them across the globe.
"You can set up your own little library," said Ewart. "It doesn't have to be fancy or cute or anything."
Little Free Library owners we spoke with said it's a way to promote literacy, and they hope to see more structures like these lining the streets.
"The more active, engaged readers you have, the stronger and healthier the community is," said Sweedler DeHart.
Pullman also has a Little Free Library, and we're told there are a few in the Valley as well. If you want to find a map of all the registered Little Free Libraries, check out their website