Music Album artwork

Little tip:
If you have lots of bootlegs etc. you want to bring your embedded metatags into order first.
Then you need to have the Local Media Assets agent in top position. I wouldn’t trust last.fm to fetch correct info about bootlegs and special editions of albums, like those recent expanded re-releases of Zappa albums.
Put as much info into the meta tags as possible. Put a cover art inside the album folder and you should be good.
Makes sure to set at least ‘AlbumArtist’ and ‘AlbumTitle’ to the same content within one album.

I have collected some more info in the thread below. Although it talks about a Premium Music library, the stuff about file names and embedded meta tags applies to a normal music library just the same.

And here is another cut&paste from the Plex Pass forum:

You can supply your own artist photos, artist backdrops and album backdrops.
This however requires that your music files are organised in a folder structure like this:

Music /
|--Albumartistname /
   |  artist-poster.jpg      <--- a photo of the artist
   |  artist-background.jpg  <--- a background/wallpaper particular to the artist
   |--Albumtitle /
         cover.jpg           <--- album cover
         background.jpg      <--- album background/wallpaper [if not present, inherited from the 'albumartist' level]
         1. Trackartist - Tracktitle.mp3
         1. Trackartist - Tracktitle.txt
         2. Trackartist - Tracktitle.mp3
         2. Trackartist - Tracktitle.lrc
         ...

The graphic files can be in jpg, png, or tbn format. For all filenames there are a few alternative names which can also be used.

The txt files can contain the song lyrics in plain text format.
The lrc files can contain the ‘timed’ song lyrics.