Marhaba! HANY...
JNF (Jewish National Fund) stamps were fund raising stamps. When first issued, they were distributed to 17 countries around the world. If I remember correctly, the stamps were one color sheetlets of 20 or 25 stamps each showing images go scientists, doctors, teachers, leaders, etc.; there were multiple images per sheets with a few exceptions (Theordore Hertzl, State of Israel). When a donation was given a stamp was offered in exchange. Children normally collected the stamps in little booklets.
Two (or more) of the JNF stamps -- the Theordore Hertzl and Map of Israel issues -- acted as "Local postal issues" or "Mandate postal issues" shortly before/after Israel Independence in May 1948. These two issues postally used on and off cover are sought after by collectors.
FROM WIKIPEDIA:
https://en.wikipedia.org/wiki/David_WolffsohnDavid Wolffsohn ; 9 October 1856 in Darb#279;nai (Polish: Dorbiany), Kovno Governorate – 15 September 1914) was a Lithuanian-Jewish businessman, prominent early Zionist and second president of the Zionist Organization (ZO).
David Wolffsohn was born in Darb#279;nai, Lithuania, to religious parents, Isaac and Feiga. He received an observant religious education from his parents and in 1872 was sent to Germany to avoid conscription into the Russian army. He settled in Memel, East Prussia where he met Rabbi Isaac Rülf, who accepted him as a student. Rülf taught Wolffsohn the German language and mathematics, and introduced him to the Hovevei Zion movement. (much more click on link
https://en.wikipedia.org/wiki/David_Wolffsohn)HANY, I hope that helps.
As-salam alaykom,
Hal