Conversation so far:
When did the Byrds form?
In early 1964 they began to assemble a band that would become the Byrds.
Who were the original members?
fellow folkie and Beatles convert Jim (later Roger) McGuinn.
Anybody else?
David Crosby and became the tambourine and harmonica player.
Bassist Chris Hillman.
What was his role in the band?
Clark wrote or co-wrote many of the Byrds' best-known originals.

Question: What songs were those?
Self-contained rewrite: What Byrds songs were written or co-written by Clark?