We do it in A Dorian, which if you are not familiar with the modes that folk music seems to get written in that's a G scale starting on A, sort of a minor 6th or something.

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  Am                 G        Am        G  Am
  A blacksmith courted me, nine months or better
      Am            G            Am   G  Am
  He fairly won my heart, wrote me a letter
             G             Am       C         Am G
   With his hammer in his hand, he looked so clever
           Am          G  Am            C Am    GAm
  And if I were with my love, I would live forever

Hope this helps, you can play a lot with the chords using the G-C-D pattern as the sound of the song allows for some almost disharmonic(?) sounds, eg the second G on the first two lines could also be a C or D to give a weird harmony against avoice.

Slán,

BB