A variation of the clawhammer pattern that sounds interesting is to play another note with the middle (m) finger at the same time as the first thumb (p) note i.e.: Q . This technique is called the pinch.
Q indicates that the thumb (p) and middle (m) fingers play together. Here is pattern 7a applied to a C chord.
The progression in the next exercise contains chords that are based upon the C and Am chord shapes.
C

Cmaj7

Cadd9

Am

Am add9

Asus

Fingerpicking Pattern 7a