  We report multi-differential measurements of strange hadron production
ranging from mid- to target-rapidity in Au+Au collisions at a
center-of-momentum energy per nucleon pair of $\sqrt{s_{\rm NN}}=3$ GeV with
the STAR experiment at RHIC. $K^0_S$ meson and $\Lambda$ hyperon yields are
measured via their weak decay channels. Collision centrality and rapidity
dependences of the transverse momentum spectra and particle ratios are
presented. Particle mass and centrality dependence of the average transverse
momenta of $\Lambda$ and $K^0_S$ are compared with other strange particles,
providing evidence of the development of hadronic rescattering in such
collisions. The 4$\pi$ yields of each of these strange hadrons show a
consistent centrality dependence. Discussions on radial flow, the strange
hadron production mechanism, and properties of the medium created in such
collisions are presented together with results from hadronic transport and
thermal model calculations.
