"Tales of Earth" is the title of a series of backup stories that appeared in the Generation 2 comic book. It's not quite that simple, however, as "Tales of Earth" was an integral part of the "main" story in most issues; any attempt to read "Tales of Earth" as a separate story would basically lead to total confusion. And it wasn't always a "backup" story, either; sometimes it would appear before or even in the middle of the main story.