Ark. Agricultural Experiment Station | Flickr
University of Arkansas. Good cotton, rice pics.
Ag Photos
Library: U.S. Department of Agriculture | Flickr
Probably the best place to look for ag photos.
Library: North Carolina – Mark Stebnicki Photography | Pexels
North Carolina (most), Arizona, and California pics. Beautiful shots.
Album: FNS-Farm to School at Royalton-Hartland SD in Niagara County, New York | usdagov/Flickr
Album: Food, Nutrition, and Consumer Services In Washington D.C. | usdagov/Flickr
Library: Montana NRCS | Flickr
Library: Texas NRCS | Flickr
This isn't the most organized library, but can be good if you know what you're looking for.
Library: Oregon NRCS | Flickr
Library: New Mexico NRCS | Flickr
Library: Wisconsin NRCS | Flickr
Library: New York NRCS | Flickr
Not that many pics, but some adorable calves and good people pics.
Library: Alabama Extension | Flickr
Library: Kansas State Research and Extension | Flickr
Library: Georgia – UGA CAES/Extension | Flickr
College of Agriculture and Environmental Sciences, Georgia
Library: Missouri – Mizzou CAFNR | Flickr
University of Missouri
Library: Missouri – MUExtension417 Extension | Flickr
Library: Oregon State University | Flickr
Not all photos are public domain / creative commons, so double check
Library: Washington State Department of Agriculture | Flickr
Library: Oregon Department of Agriculture | Flickr
There are some good pics here, but some are dated
Album: McKee-Beshers Wildlife Management Areas Sunflowers | usdagov/Flickr
Nice pollinator, insect, sunflower pics
Library: California kqedquest | Flickr
Not strictly ag pics
Album: PA Good Harvest Farm Blossoms from Energy Savings | usdagov/Flickr
Pics of using energy, water
Album: Agriculture Research Service (ARS) | usdagov/Flickr
Album: Precision Agriculture Frick Farms | usdagov/Flickr
Album: Nonlethal Methods for Wildlife Damage Management | usdagov/Flickr
Library: Land Between the Lakes KY/TN | Flickr
US Forest Service, Kentucky and Tennessee
Album: Montana – Beaverhead-Deerlodge National Forest | usdagov/Flickr
Album: Salmon | usfwspacific/Flickr
Library: Massachusetts – Terry Donovan | Flickr
Beautiful animal shots, often closeup portraits
Album: Massachusetts – Chickens, Terry Donovan | Flickr