Shortcode to flag is an easy plugin, that will allow you to insert flags with shortcodes. For example, US will change to an American flag that won’t break your formatting. The height of the flags is 40pixels.
Usage
Put country code (in capital letters) to shortcode to display desired flag.
e.g. [US]
Edits
If you want to change height of the flags, do so in file flagstyle.css
This plugin is available for download for your site.