Hi Ladyhawk,
I don't know if this is your one...but there's a Mary Jane Smith on the 1891 Census for Wales, living in Cardiff, with:
Frederick J Smith 29yrs
Mary Jane Smith 29yrs (Born Cardiff).
William S Smith 8yrs
Edgar F Smith 8/12mnths
Dennis Collins 69
There's also a Birth Entry for an Ellen Mary Smith, born Cardiff, April/May/June Quarter of 1861 11a 263.
HTH, Romilly.