Amongst a collection I purchased a couple of years ago, I came across some postcards with Scout cachets from the Estonian War of Independence of 1918-1920.  I had known nothing about these items or about the war until I researched these, before adding them into my collection.  When the German troops were leaving Estonia in late 1918, Soviet Russia wanted to invade Estonia and establish Bolshevist power.  On 28 November 1918 the Red Army started an offensive to the border town Narva and thus began the armed conflict between Soviet Russia and the Republic of Estonia.  The Estonian government nevertheless decided to oppose the Bolshevist aggression, hoping for help from the Western countries (i.e. the former Russian allies in World War I) and Finland.  They were not let down — in December 1918, the British Royal Navy arrived in Estonia with a cargo of weapons; Finland also sent weapons and in January 1919 about 4000 volunteers came too.  The conflict lasted until February 1920, which resulted in a victory for Estonia and was concluded by the Treaty of Tartu.  The Estonian Field Post Offices were estab- lished on 11 January 1919 and continued until 15 May 1920.  Most boys including Scouts over 16 (many even younger) volunteered for the fighting forces and were also responsible for some of these Field Post Offices.  There were many hundreds of these cachets, and the book "Estonia Philately & Postal History Handbook" by Vambola Hunt and Elmar Ojaste published in 1986 gives within its 600 pages, details of all known ones and includes details of the 13 Scout cachets.
I received the Felzmann Auction Catalogue No. 132 from Germany which weighed 1793 grams (3.95 lbs) despite only having four Scout lots out of many thousands.
Amongst this was a postcard (Lot 7351) sent from Lausanne, Switzerland to Paris on 10 August 1900.  Described as showing a Scout camp, the postcard did at least show tents, but as we all know Scouting did not start until 1908!
I note that Profila, the major Hungarian Auction house had a Scout auction last month of Philatelic and Jamboree ephemera.  However their prices are not realistic in today's market and only 36 out of 412 lots sold.  Over the years since the end of communism, a considerable amount of material has come to the market, as the Hungarians have always been serious stamp collectors.  Whenever I go to Budapest I always attend the Mabeosz stamp meeting on a Thursday afternoon, in the building that the Hungarian Stamp Association own in Vorosmarty u. 65.  Here over two floors are numerous small dealers who sell their wares, both of post postcards and stamps.