Let's Play Music : Easy Piano Sheet Music for Old MacDonald Had A Farm
Not only is this a good sheet to start with, it's a classic everyone should know.
Major Keys Chord Chart. I'm pinning this just in case, but I'm fairly certain I can do all of that in my head since, you know, I have a music degree.
A basic discussion of scales and chords. Music-infographic-8x25
Chord Progression Chart by Wayne Chase - How Music Really Works