Wow! Seems to be a brickwall of monumental proportions? If this was my family, I'd call Mitchell County Clerk and request "lookup in marriage index for surname Smart females to any males, 1880-1900". Hopefully she had sisters and you'll be able to trace them? If that proves worthless, I'd call back and ask for surname Smart males during the same timeframe. Either lookup will have minimal impact on the clerks. All Texas Counties maintain marriage indexes: groom-to-bride (and vice versa) for specific time periods. One family tree dates her marriage 30 Sep 1890 and you'll not find an official birth record for Bessie Elizabeth, 11 Nov 1891, or death record for her mom. Texas mandated vital records effective 1903. Compliance with the law was spotty for several decades thereafter. From daily research, I'm amazed to find people buried in 1950s with no official records.