The pattern I can't get out of my head right now is the tattersall check. It may look familiar. It's a popular pattern for the English countryside. I imagine there is a look book or two out there with guys in tattersall check shirts and jackets leaning against land rovers, wearing Le Chameau boots, and a spaniel sitting regally at heel.
Via alexander-west.com, the pattern is described as follows:
Tattersall is a check pattern that consists of thin, regularly spaced stripes in alternating colors that are repeated both horizontally and vertically. The stripes that create the tatersall pattern often come in two different colors and are usually darker than the background color.
The tattersall check can vary in size, causing the squares to be larger or smaller. If smaller, and you plan on wearing a tie, you can treat the shirt as a solid, and choose from a wide variety of tie patterns. Also, I recommend a button down collar, as it gives you greater flexibility to wear it dressed up or more casual.
Although originating in England, I've seen the pattern flare up in warmer colors, sometimes even pastels in the American south. If that's your end game, Ralph Lauren, Peter Millar, and Brooks Brothers, are good places to look.
Overall, the tattersall is a great pattern for a shirt if you already have your basic solids. It can be dressed up and down, and comes in a variety of colors and sizes.