There is a lot of music in Plants vs. Zombies: Retro Attack.
This is the Grasswalk Theme of PvZRA. It is a mashup of the PvZ1 and PvZ2 versions of Grasswalk.
BossIsHereToKellU (seriously, that's the name.):
The boss music, which is a mashup of the Far Future and Frostbite Caves Ultimate Battle Themes.
This is the theme played in the intermission levels, which are singular between worlds. The song was the Frostbite Cave Choose Your Seeds music. It was later changed to the music heard when opening the PvZ2 Yeti's lunchbox. Currently, it's the PvZ2 World Map theme.