Looks like a stray verse from 'I've Rambled This Country Both Earlye, and Late' (Roud 1795) in Our Singing Country; John A. Lomax & Alan Lomax, 1941, pp.143-144. Sung by James Mullins, Morgan County, Kentucky.

I wish I were a fisherman on yon riverside,
Pretty Polly my object come floating down the tide;
I'd throw my net round her, I'd bring her to the shore,
And have Pretty Polly to weep for no more.

Matthew