I honestly would suggest the Charlie Brown collection of music. There's a book of sheet music with big notes that I have if you want me to link you to it so you can see if you want to buy it.

It has bass, of course, and treble simultaneously. It's fairly simple music but challenging enough for a beginner, and it's recognizable so you'll know if you're playing it correctly.

you must understand that your ears and your hand are your most valuable possessions as a beyboardist.....i advice u listen to blues where u can develope your hearing capabilities.if u are learning with staff, then get the music sheets online to try them. but i advice u work on all your major chord, be familiar with them, then work on chromatic chords then u will be able to understand when a chord is been played... hope this help....