  Eclipsing binaries provide a unique opportunity to determine fundamental
stellar properties. In the era of wide-field cameras and all-sky imaging
surveys, thousands of eclipsing binaries have been reported through light curve
classification, yet their basic properties remain unexplored due to the
extensive efforts needed to follow them up spectroscopically. In this paper we
investigate three M2-M3 type double-lined eclipsing binaries discovered by
cross-matching eclipsing binaries from the Catalina Sky Survey wtih
spectroscopically classified M dwarfs from the Large Sky Area Multi-Object
Fiber Spectroscopic Telescope survey data release one and two. Because these
three M dwarf binaries are faint, we further acquire radial velocity
measurements using GMOS on the Gemini North telescope with R~40000, enabling us
to determine the mass and radius of individual stellar components. By jointly
fitting the light and radial velocity curves of these systems, we derive the
mass and radius of the primary and secondary components of these three systems,
in the range between 0.28-0.42 M_sun and 0.29-0.67 R_sun, respectively. Future
observations with a high resolution spectrograph will help us pin down the
uncertainties in their stellar parameters, and render these systems benchmarks
to study m dwarfs, providing inputs to improving stellar models in the low mass
regime, or establishing an empirical mass-radius relation for M dwarf stars.
