The 9th Chord
The 9th chord (shown above) is a funk guitar staple used constantly by funk guitarists. Especially the chord on the left, with the root (notated by the red dot) on the fifth string. Be careful about playing the sixth string root 9th chord on the lower frets - it can sound very muddy.
The 9th chord is a 7th chord with one extra note, added for color. Try replacing 7th chords in songs you know with 9th chords. There are some situations where this substitution doesn't work - use your ear to tell you what sounds right.
It is also EXTREMELY common for funk guitarists to only play the top three strings when playing the fifth string root 9th chord. Sometimes, they'll even only play the top two strings.