America's heartland is a good resource 

Dairy farm:  https://www.youtube.com/watch?v=s3zO7pMvlBc&feature=youtu.be

Cattle ranch largest in US (Texas): https://www.youtube.com/watch?v=ks7-O469KPU
Cattle ranch 2nd largest in US (Florida): https://www.youtube.com/watch?v=GLETAdwgQn4

Poultry: https://www.pinterest.com/pin/56998751508278609/
Eggs: http://educationstation.discoveryeducation.com/field-trips 

Tomato (from Hunt's ketchup): https://www.youtube.com/watch?v=pJbDIaqK50U

https://www.ndfb.org/edusafe/virtualfarm/

UK: http://www.nfuonline.com/archived-content/more-news/take-your-visitors-on-a-virtual-farm-tour/