The earliest version of "The Mower" in the Bodleian Collection, as posted by Jim Dixon (with slight variations from sheet to sheet) is dated c. 1813-1838 (Catnach) and c. 1819-1844 (Pitts).

The DT copy of A. L. Lloyd has a mistake in the last verse, first line, which should read
'Oh(Now), the more she kissed and did protest, this fair maid...', not-
'Now the mower she kissed and did pretest,...'.
Otherwise only very slight differences in Lloyd from the DT.

A. L. Lloyd, Folk Song in England, 1967, pp. 188-189, with music.

The meaning of taring (tarring) scythe is obvious, but I couldn't find the adj. in the OED or Grose, except with reference to tarring (and feathering), or to tares.