Mazda Publishers an Iranian publisher in the US.

Mage Publishers another Iranian book publisher in the US.

Iran Books yet another Iranian book publisher in the US.

The Encyclopedia Iranica Edited by Dr. Ehsan Yarshater, Columbia University
The most extensive compendium ever conceived on the past and present culture of the Iranian-speaking peoples and their contribution to the broader history of human civilization.

The Iranians: Persia, Islam and the Soul of a Nation by Sandra MacKey,
A great general introduction to Iran's history. Highly recommended.

Culture Shock!: Iran by Maria O'Shea, April 1999. The Culture Shock series is intended for travellers who need a primer on local cultures, dos-and-don'ts. This one was not bad - not great, but not bad.

1001 Persian-English Proverbs by Simin K. Habibian.
A great glimpse into Iranian culture.

Prof. Erika Friedl's first-hand accounts of rural life in Iran: Children of Deh Koh : Young Life in an Iranian Village and The Women of Deh Koh : Lives in an Iranian Village