The postage stamps of the German State of Bavaria from around 1920 hold a unique place in philatelic history, particularly those issued during the transition period when Bavaria was declared a Free State ("Freistaat Bayern"). These stamps are not only valuable for their historical context but are also highly sought-after by collectors due to their rarity and distinctive features. Notable examples from this period include the 3 Pfennig Brown, the 25 Pfennig Light Grey, the 5 Mark Blue, and the 20 Mark Brown stamps, each bearing the iconic “Freistaat Bayern” overprint. In mint, unused condition (known as “postfrisch” or post-fresh), these stamps are exceptionally desirable.

The “Freistaat Bayern” overprint is a defining characteristic of these stamps, introduced following the abdication of Bavaria's last king, Ludwig III, and the establishment of a republican government. This overprint marked Bavaria’s shift from a monarchy to a free state within the newly formed Weimar Republic, symbolizing a significant political change. Collectors are particularly attracted to these stamps for their connection to a pivotal historical moment, as well as their delicate aesthetic and fine craftsmanship.

The 3 Pfennig Brown stamp is a modest denomination but stands out due to its scarcity in pristine condition. It was widely used, and as a result, finding post-fresh examples can be challenging. The 25 Pfennig Light Grey is equally rare, recognized for its subtle design and pale coloring that evokes a sense of the understated elegance characteristic of early 20th-century Bavarian philately. 

The higher denominations, such as the 5 Mark Blue and 20 Mark Brown, are especially rare and valuable. The 5 Mark Blue is celebrated for its bold hue and detailed design, representing the height of Bavarian stamp artistry. The 20 Mark Brown, in particular, commands a high value due to its limited print run and the significance of the “Freistaat” overprint on a stamp of such high denomination. These stamps were less commonly circulated, which adds to their rarity, particularly in mint condition.

In sum, Bavarian stamps from the 1920 period featuring the “Freistaat Bayern” mark are not only treasures of philatelic history but also tangible relics of Bavaria’s political transformation. Their rarity and pristine condition make them valuable collectors’ items, with each denomination carrying its own unique appeal and historical significance.