If it's a mn, then pronunciation isn't much of an issue.
Accuracy is, though, and what Pie says is accurate! An early spelling is Amyas, and the first 2 syllables sound like the modern name Amy, with an 'us' on the end.
It seems that this was recorded in Cornwall in the early 16th century. The rhythm seems to demand the AMYus pronunciation (which is also more polite than 'Uh my ass'!):
You and I and Amyas, Amyas and you and I,
To the green wood must we go
Alas! You and I, my life and Amyas
The knight knocked at the castle gate; the lady marvelled who was thereat
To call the porter he would not blin; the lady said he could not come in
Alas! You and I, my life and Amyas
The portress was a lady bright; Strangeness that lady hight
She asked him what was his name; he said 'Desire, your man madame'
Alas! You and I, my life and Amyas
She said 'Desire what do you here'; He said 'Madame, as your prisoner'
He was counselled to brief a bill; And show the lady his own will
Alas! You and I, my life and Amyas
Kindness said she would it bear; And Pity said she would be there
Thus how they did we cannot say - We left them there and went our way
Alas! You and I, my life and Amyas
http://www.livinghistory.co.uk/homepages/song-and-dance-offline/you_and_i_and_amyas.html