  Extremely high magnetoresistance (XMR) in the lanthanum monopnictides La$X$
($X$ = Sb, Bi) has recently attracted interest in these compounds as candidate
topological materials. However, their perfect electron-hole compensation
provides an alternative explanation, so the possible role of topological
surface states requires verification through direct observation. Our
angle-resolved photoemission spectroscopy (ARPES) data reveal multiple
Dirac-like surface states near the Fermi level in both materials. Intriguingly,
we have observed circular dichroism in both surface and near-surface bulk
bands. Thus the spin-orbit coupling-induced orbital and spin angular momentum
textures may provide a mechanism to forbid backscattering in zero field,
suggesting that surface and near-surface bulk bands may contribute strongly to
XMR in La$X$. The extremely simple rock salt structure of these materials and
the ease with which high-quality crystals can be prepared suggests that they
may be an ideal platform for further investigation of topological matter.
