  Using data from the MEarth-North and MEarth-South transit surveys, we present
the detection of eclipses in four mid M-dwarf systems: LP 107-25, LP 261-75, LP
796-24, and LP 991-15. Combining the MEarth photometry with spectroscopic
follow-up observations, we show that LP 107-25 and LP 796-24 are short-period
(1.388 and 0.523 day, respectively) eclipsing binaries in triple-lined systems
with substantial third light contamination from distant companions. LP 261-75
is a short-period (1.882 day) single-lined system consisting of a mid M-dwarf
eclipsed by a probable brown dwarf secondary, with another distant visual brown
dwarf companion. LP 991-15 is a long-period (29.3 day) double-lined eclipsing
binary on an eccentric orbit with a geometry which produces only primary
eclipses. A spectroscopic orbit is given for LP 991-15, and initial orbits for
LP 107-25 and LP 261-75.
