Each of the major characters in Thud! and thus the resolution (of sorts) of the ambiguity (who won if anybody) of the Battle of Koom Valley have appeared on Discworld Stamps.
On the troll side is Mr Shine (Him Diamond), king of the Ankh-Morpork trolls. He was the subject of a diamond shaped (obviously) three-penny stamp issued in the year of the Second Inception. For a full KV collection you may want to add the inverted image sport and the ful sheet of stamps.
For the dwarfs is Rhys Rhysson, king of the Low Dwarfs. He appeared on a 30 Bizot stamp fom Ãœberwald issued in the Year of the Reciprocating Llama. In fact the stamp labeled Rhys Rhysson is the sport on the sheet. These stamps were issued after Rhys had revealed herself to actually be Queen of the Low Dwarfs and called Blodwen.
Keeping the two factions apart was the Ankh-Morpork City Watch led by Commander Sam Vimes. He finally made an appearance on a $1 stamp in the Year of the Spinning Mouse. There are both blue and purple versions of this stamp, and pictured below is the sport which shows the mark of the Summoning Dark which Vimes acquired in Koom Valley.