Very powerful symbols make for very powerful magic items. Here's six...
Flag of Doom
Those who behold the flag of doom within a distance of sixty feet are immediately filled with fear and must make a saving throw or else hightail it for d6 turns. Those who make their saving throw still suffer a -4 to any morale rolls made during the encounter.
Flag of Allegiance
Those who behold this flag within sixty feet must make a saving throw or else are charmed by the flag bearer and will surround and follow him, protecting him and the flag with their lives if necessary. The spell is only broken if the flag should touch the ground or if the bearer can be interpreted in any way as disrespecting it.
Flag of Duplicity
A cursed piece of cloth, this item first appears to be the flag most favored by those who unfurl it. Viewed from a distance greater than 100’ though, its colors change to become the most dangerous flag for its bearers or the one who hoisted it depending on the situation. For example, it might become totally white, signifying surrender, or it might become the flag of the enemy on a battlefield, or it might suddenly become the Jolly Roger on the high seas when a friendly navy vessel comes into sight, etc.
Flag of Mirth
Unfurled and hoisted, anyone within 100’ who beholds this flag will be overcome with goodwill for everyone else in sight (save allowed) with the effect lasting a full day. Indeed, a celebratory atmosphere will quickly descend on the area, with spontaneous singing, dancing, and general all around back slapping. Needless to say, any alcohol or food in the area will be shared and consumed in earnest by those affected - although no one will want to leave the area of effect in search of more.
The Yellow Flag of Holding
A small yellow flag - if taken from storage and thrown to the ground, all those in a 30’ diameter area must make a saving throw or else be immobilized (treat as Hold Person spell.) It can only be used once per day.
Flag of Bafflement
Once per day, this flag can be used to cause up to twenty creatures who see it at ranges of less than 120’ to become confused for two hours. On a roll of 2d6, the creatures will do the following:
2-4 Attack Bearer & His Allies
5-9 Stand baffled and debate the flag’s design/meaning.
10-12 Attack each other.
The dice are re-rolled every ten minutes for the duration of the two hours.
If you live in the U.S., Happy Independence Day!