Watch the Working with a I IV online guitar lesson by Vicki Genfan from Acoustic Rhythm Survival Guide
The I and IV chords are considered, along with the V chord, to be the 'Basic' building blocks of thousands of songs. (The IV-I is sometimes referred to as a 'Plagal' or 'Amen' Cadence because of its frequent use in Hymns.) Some additional songs you may know that use this progression are In the Midnight Hour by Wilson Pickett, One More Night by Phil Collins, Love Me Do by the Beatles, Rocket Man by Elton John, and Some Kind of Wonderful by Grand Funk.
(Songs I played: Do you believe in Magic, Imagine, You can't always get what you want. What else??)