First of all, you need to know that a lot of popular music is not written in standard English. Bob Marley's lyrics contain features of Jamaican dialect, so it's not the best way to learn English! The other thing you should realise is that the lyrics that you read online are often wrong, because they've been transcribed and posted by fans who may have misheard what was being sung.
As for this line, I believe the correct lyrics are 'They sold Marcus Garvey for rice.' I've listened to the song, and that is what he seems to be singing.