Something that's famed is very well-known, or famous. Your dad's famed brownies are the highlight of every bake sale in town.
The adjective famed basically means "renowned." In other words, something that's famed is famous, usually for its excellence. If a book is famed, it's either a bestseller or a classic, and if your English teacher is famed, it's probably hard to get into her classes because everyone wants to take them. The 16th century meaning of famed was "much talked about," from the now-obsolete verb fame, "spread abroad or report."