A pretty simple progression, Chloeanned.

Lead Belly is pretty close to C.

Relax your [C] mind, relax your [C7]mind,
And you'll [F] feel so fine some[C]times,
Sometime, you [G] got to relax your [C] mind.

Sometimes I like to play it:

Relax your [C] mind, relax your [C7] mind,
And you'll [F] feel so fine [F#dim] sometimes,
Some[C]time, you [G] got to relax your [C]mind.