For better or worse, we've noticed a lot more gentleman wearing pocket squares of late. As a fashion accessory, we whole heartedly endorse it. Keep in mind, the pocket square need not match the tie. In fact, it is preferable that it doesn't.
Some of our favorite pocket squares are made by Liberty in London. The image above is a selection of Liberty pocket squares. We are big fans of the embroidered edge, though they do make them in finished edges as well.
The liberty store (and even better the Liberty duty free at Heathrow) are the best place to find the pocket squares (as well as a host of beautiful ties and shirts). We did find this store, Robert Redd, online that makes their own pocket squares from Liberty fabrics.