Agree with HKUSP45C. Kohls and WalMart have a pretty good selection for a reasonable price. These are also called "camp shirts". I wear short sleeves in the Summer and long sleeves in the Winter. It is hard to find the long sleeves, but 2 companies make them that I am aware of (I'm sure many more do)...
Batik Bay...Kohls
Monte Carlo...WalMart
They are nice enough to wear anywhere and meant to wear not tucked.