We have a new special interest group at ROS-Agriculture (https://discourse.ros.org/t/ros-a-sig-datasets/13011). We are researching public domain ag datasets and annotation tools. After this list is compiled it will be publicly available. Here is a prior list of datasets: http://wiki.ros.org/agriculture
Recording of first meeting today: https://youtu.be/qcwmLOMys90
If you know of any datasets we would love to include them.