He wrote more articles than books. I think you kind of have 2 routes to go:

1. The Academic Primary Text Route and pick up either a reader like Menand’s “Pragmatism: A Reader” or get “The Essential Peirce” which comes in 2 volumes to see the actual work.
2. The Historical Route and pick up Louis Menand’s “The Metaphysical Club” which is a historical accoutthat defines this emerging American thought based on a dinner club that featured Philosophers Charles Peirce and William James, and Supreme Court Justice Oliver Wendall Holmes Junior.

I think 2 is probably good if you want more historical context, narrative, and summary of their ideas, but route 1 gives you the direct text which is less accessible for casual reading in my opinion. I will say that I do sometimes think James is correct in his criticism of Peirce’s writing being “flashes of brilliant light relieved against Cimmerian darkness.”