  We calculate the baryon asymmetry created by the decay of a pseudo
Nambu-Goldstone boson whose interactions violate baryon number conservation.
Our results are in disagreement with previous results in the original
spontaneous baryogenesis models for the asymmetry produced by the decay of an
oscillating scalar field with B number violating derivative couplings; we find
that the net baryon number density is proportional to $\th_i^3$, where $\th_i$
is the amplitude of the PNGB-field in natural inflation at the onset of
reheating. We also discuss our disagreement with the interpretation of
$\dot\theta$ as an effective chemical potential for baryon number in
spontaneous baryogenesis models. While our calculation of the asymmetry is
carried out in the context of natural inflation our approach is generally valid
for baryogenesis models using decaying classical fields. In the Appendices, we
include a complete derivation of the number density of particles produced by
the decay of a classical scalar field; this number density is proportional to
the integral over momenta of the one pair production amplitude.
