  We report a study of the Mott insulator La$_2$O$_3$Fe$_2$Se$_2$ by means of
$^{139}$La nuclear quadrupole resonance (NQR). The NQR spectra evidence a
single La site in the paramagnetic phase and two inequivalent La sites, La1 and
La2, in the antiferromagnetically-ordered phase (N\'eel temperature $T_{\rm{N}}
\simeq 90$ K). These two sites are characterized by different quadrupole
couplings, indicative of distinct lattice and/or charge configurations likely
segregated in domains. The dependence of the quadrupole coupling for La2 on
temperature suggests that the magnetic order parameter drives the structural
distortion. The nuclear spin-lattice and transverse relaxation rates, $1/T_1$
and $1/T_2$, evidence fluctuations in the paramagnetic phase with
characteristic frequencies well below the Heisenberg exchange frequency, likely
associated with nematic fluctuations.
