Bean Farm (Twisting Vines and Weeping Vines). Produces a total of 678,000 items per hour:

--- 347,000 Twisting Vines. --- 331,000 Weeping Vines.

They just need to pull any of the levers next to the bulk or even both to turn it on. It uses a lot of bone meal, so make sure the chests in front of the levers are filled with shulker boxes of bone meal so that the dispensers stay charged and the vines can grow. It has a bulk of 11 slots, an automatic blue shulker crafter, a chunk loader to leave it AFK, and a collection system based on minecarts with hoppers.