Flags
You can place banners as flags by sneaking when placing the banner.
Flags & banners can be extend by placing a new banner (no matter which color) on the current flag or banner.
Flags & banners can be broken by hiting the flag or banner. Larger flags & banners will drop multiple banner items.
Switch to of hand to place a regular banner on a chest, door or any blocks where you can't place banner on it without sneaking.
See the GitHub for more info.