Here is the cover for "History of Sonic Music 20th Anniversary Edition" CD. It's marked with the "20th Anniv" seal/logo thing in one corner, and has a CG Sonic running in a winged ring with stars. The cover is pretty plain, and doesn't mention anything that could be inside.
This likely has a track or two from...probably as many games as they could fit onto a CD. Since it's called "History of..." it's probably attempting to be a good sampler of the music of all of the eras of Sonic. Do write in if you know which games have music on this CD.