Not sure what's up with that kid's hair, but here is a c.1866 tintype photograph of a woman breastfeeding, from the collection of the late filmmaker Gary Winick.
I am sure it's just a coincidence that Winick was a producer on Chelsea Walls, the 2001 directorial debut of Ethan Hawke, which included his then-wife and baby mama, the noted lactivist Uma Thurman.
From the collection of Gary Winick, Apr 4, 2012, Lot 170: Tintype, est. $800-1,200 [swanngalleries]
Chelsea Walls (2001) [imdb]
I don't think that baby is nursing.
The baby's head position is wrong - if it were nursing, we would only be able to see the back of its ears, and pretty much none of its face, which would be facing into the mom's chest.
I'm all for breastfeeding (breastfed twins, even) but this isn't a breastfeeding picture.
a good point. maybe it was staged as a nursing photo.
I think the sitter intended it as a picture of herself and her baby only. As far as I know, nursing photos were not a common early photography theme, and this one doesn't even look like an attempt.