The creators of the site tell us what it’s all about:
This project aims to make more available the natural food sources throughout the city that go undiscovered each year. Nut trees, berry patches, unsprayed fields of dandelion roots are all welcome. We invite you to share the sources you already know of, search for new ones with your friends, and participate in our official scouting days.
They provide a succinct list of ethical considerations (e.g. “Will my harvesting leave an impact?”, and “Does this plant need any care after harvest?”). You can search by location or browse by category.