  Differential cross sections and photon beam asymmetries for $\pi^0$
photoproduction have been measured at $E_\gamma$ = 1.5--2.4 GeV and at the
$\pi^0$ scattering angles, --1 $<$ cos$\Theta_{c.m.} <$ --0.6. The
energy-dependent slope of differential cross sections for $u$-channel $\pi^0$
production has been determined. An enhancement at backward angles is found
above $E_\gamma$ = 2.0 GeV. This is inferred to be due to the $u$-channel
contribution and/or resonances. Photon beam asymmetries have been obtained for
the first time at backward angles. A strong angular dependence has been found
at $E_\gamma >$ 2.0 GeV, which may be due to the unknown high-mass resonances.
