Everything #OpenStreetMap related is welcome: software releases, showing of your work, questions about how to tag something, as long as it has to do with OpenStreetMap or OpenStreetMap-related software.
OpenStreetMap is a map of the world, created by people like you and free to use under an open license.
Join OpenStreetMap and start mapping: https://www.openstreetmap.org.
There are many communication channels about OSM, many organized around a certain country or region. Discover them on https://openstreetmap.community
https://mapcomplete.org is an easy-to-use website to view, edit and add points (such as shops, restaurants and others)
https://learnosm.org/en/ has a lot of information for beginners too.
Well, it's OpenStreetMap, you can basically tag anything. Although I've never seen something like a dedicated flag disposal here in Europe, you could combine amenity=waste_basket + waste=flags.
waste=flags is only used twice to this date, however. See taginfo.
How this data is used, however, is up to the renderers/data consumers.
