Listening to the Light: Jim Pym
This is short introduction to Quaker practices including worship, personal practice, and the Quaker business method. This is less about Quaker history and more about praxis.
The Journal of George Fox
George Fox is often considered to be the founder of the Religious Society of Friends (Quakers). His personal journal is a popular read within the faith.
The Quakers: A Very Short Introduction
This provides a good, short history of Quakerism as well as topics surrounding "the Quaker Way," including the practice of Quaker worship (i.e. Inner Listening).
Living the Quaker Way: Philip Gulley
This is, again, more about "the Quaker Way" in general terms than about specific spiritual practices. A well-rounded look at the faith.