  We present extensive photometric and spectroscopic observations of the nearby
Type Ia supernova (SN) 2023wrk at a distance of about 40 Mpc. The earliest
detection of this SN can be traced back to a few hours after the explosion.
Within the first few days the light curve shows a bump feature, while the B - V
color is blue and remains nearly constant. The overall spectral evolution is
similar to that of an SN 1991T/SN 1999aa-like SN Ia, while the C II
$\lambda6580$ absorption line appears to be unusually strong in the first
spectrum taken at $t \approx -$15.4 days after the maximum light. This carbon
feature disappears quickly in subsequent evolution but it reappears at around
the time of peak brightness. The complex evolution of the carbon line and the
possible detection of Ni III absorption around 4700 {\AA} and 5300 {\AA} in the
earliest spectra indicate macroscopic mixing of fuel and ash. The strong carbon
lines is likely related to collision of SN ejecta with unbound carbon,
consistent with the predictions of pulsational delayed-detonation or
carbon-rich circumstellar-matter interaction models. Among those carbon-rich
SNe Ia with strong C II $\lambda6580$ absorption at very early times, the
line-strength ratio of C II to Si II and the B-V color evolution are found to
exhibit large diversity, which may be attributed to different properties of
unbound carbon and outward-mixing $^{56}$Ni.
