Mumford & Sons has a musical past that was exposed on Jimmy Kimmel Live! Monday night (8/17)... 

The boy-band "Mum-Town" is something they'd rather forget...

Meanwhile, as we all know, the band has grown and matured.  Perhaps it took "Mum" to leave the band.  Or, maybe it was the discovery of the banjo.  Or perhaps its the pure, raw talent of the core four who went from Mum-Town to Mumford and Sons.