I apologize in advance if I don't have all the accents etc correct on the Spanish words. Efemérides are anniversaries. This stamp celebrates the 40th anniversary of Tragsa (Empresa de Transformación Agraria, S.A.) an organization that works in wildlife and wilderness conservation and improvement.
The other stamp, featuring an origami elephant and her calf, is the winner of a stamp designing competition. I think this is a particularly nicely designed stamp, with a strong message. E is also for Eduardo, the first name of the designer.
Thanks for using these stamps, Eva.
For more E stamps, check out the links at Sunday Stamps.