  The large amount of chemical and kinematic information available in large
spectroscopic surveys have inspired the search for chemically peculiar stars in
the field. Though these metal-poor field stars ([Fe/H$]<-1$) are commonly
enriched in nitrogen, their detailed spatial, kinematic, and chemical
distributions suggest that various groups may exist, and thus their origin is
still a mystery. To study these stars statistically, we increase the sample
size by identifying new CN-strong stars with LAMOST DR3 for the first time. We
use CN-CH bands around 4000 \AA~to find CN-strong stars, and further separate
them into CH-normal stars (44) and CH-strong (or CH) stars (35). The chemical
abundances from our data-driven software and APOGEE DR 14 suggest that most
CH-normal stars are N-rich, and it cannot be explained by only internal mixing
process. The kinematics of our CH-normal stars indicate a substantial fraction
of these stars are retrograding, pointing to an extragalactic origin. The
chemistry and kinematics of CH-normal stars imply that they may be GC-dissolved
stars, or accreted halo stars, or both.
