Matt,I have a pocket square which is a perfect version of the latter, and find that it harmonizes with just about everything
If you post a picture of your pocket square or email me a pic, I will send take when I am next in London with Michael Drake.
Yes, the olive green, navy blue and a good brown would be a great start. The creamy white with a brown dot would be good in the second round choices in time for Spring
Cheers
Michael