One thing about gleaning (what Yarrow suggested): ASK FIRST!! At least TRY to find the owner or a manager and request permission to glean. Assure them you don't expect perfection, and that you hate lawyers and lawsuits.
It isn't so much that they're greedy, as they're gunshy- a lawsuit because someone breaks an ankle in an irrigation ditch, or "got sick" from some gleaned potatoes or tomatoes can cost them a good part of their profits... even if they win.
Maybe offer to donate a certain percentage of what you glean- 10%- IN THE FARM's NAME- to the local soup kitchen or food pantry.
Somehow, you have to find a way to distance yourself from the pure users and takers, in the mind of the folks who can help you out if they will.
Summerthyme