  We present the discovery of twelve thus far non-repeating fast radio burst
(FRB) sources, detected by the Canadian Hydrogen Intensity Mapping Experiment
(CHIME) telescope. These sources were selected from a database comprising of
order $10^3$ CHIME/FRB full-array raw voltage data recordings, based on their
exceptionally high brightness and complex morphology. Our study examines the
time-frequency characteristics of these bursts, including drifting,
microstructure, and periodicities. The events in this sample display a variety
of unique drifting phenomenologies that deviate from the linear negative
drifting phenomenon seen in many repeating FRBs, and motivate a possible new
framework for classifying drifting archetypes. Additionally, we detect
microstructure features of duration $\lesssim$ 50 $\mu s$ in seven events, with
some as narrow as $\approx$ 7 $\mu s$. We find no evidence of significant
periodicities. Furthermore, we report the polarization characteristics of seven
events, including their polarization fractions and Faraday rotation measures
(RMs). The observed $|\mathrm{RM}|$ values span a wide range of $17.24(2)$ -
$328.06(2) \mathrm{~rad~m}^{-2}$, with linear polarization fractions between
$0.340(1)$ - $0.946(3)$. The morphological properties of the bursts in our
sample appear broadly consistent with predictions from both relativistic shock
and magnetospheric models of FRB emission, as well as propagation through
discrete ionized plasma structures. We address these models and discuss how
they can be tested using our improved understanding of morphological
archetypes.
