  One of the striking observations from the Parker Solar Probe (PSP) spacecraft
is the prevalence in the inner heliosphere of large amplitude, Alfv\'enic
magnetic field reversals termed 'switchbacks'. These $\delta B_R/B \sim
\mathcal{O}(1$) fluctuations occur on a range of timescales and in {\em
patches} separated by intervals of quiet, radial magnetic field. We use
measurements from PSP to demonstrate that patches of switchbacks are localized
within the extensions of plasma structures originating at the base of the
corona. These structures are characterized by an increase in alpha particle
abundance, Mach number, plasma $\beta$ and pressure, and by depletions in the
magnetic field magnitude and electron temperature. These intervals are in
pressure-balance, implying stationary spatial structure, and the field
depressions are consistent with overexpanded flux tubes. The structures are
asymmetric in Carrington longitude with a steeper leading edge and a small
($\sim$1$^\circ$) edge of hotter plasma and enhanced magnetic field
fluctuations. Some structures contain suprathermal ions to $\sim$85 keV that we
argue are the energetic tail of the solar wind alpha population. The structures
are separated in longitude by angular scales associated with supergranulation.
This suggests that these switchbacks originate near the leading edge of the
diverging magnetic field funnels associated with the network magnetic field -
the primary wind sources. We propose an origin of the magnetic field
switchbacks, hot plasma and suprathermals, alpha particles in interchange
reconnection events just above the solar transition region and our measurements
represent the extended regions of a turbulent outflow exhaust.
