Welcome to the forum!
As Peter said, they are not stamps. They are "Spendenmarken" for the German Youth Hostel organization, "
Deutsche
Jugend
herberge
A Spendenmarke is a stamp you would receive for donating to an organization. They weren't redeemable but they are collectable.
Yours look like they are from the Hitler era but I have no pictures or references to verify that.
Dan
