Being the kind of place that Portland is, there are lots of Free Library sites around. They are on the edge of the lawn, homemade, and filled with a variety of books. One problem with them are the people who drive around, grab the good stuff, and sell them. I don’t know if they stock their stores or take them in for sale. But, unfortunately, this happens.
Rather than getting disappointed one local free librarian has taken the matter into their hands. They had a stamp made. And a warning sign for the outside of their library. The would be reseller is warned.