I'm so glad to have found this thread, as this is an experiment I am going to undertake for next year. The guy that promoted this BTE gardening method plants his next year's potatoes each year when he harvests his potatoes...he picks out the biggest one and puts it back in the ground. Been doing that for 11 yrs now? Using the same potatoes in the same place in all that time. Impressive!
Anyhoo, I'd like to take that further and plant many of my veggies that are known to grow as volunteers in the spring. I had started tomato seedlings inside this year and, after setting them out, found a tomato volunteer outside my chicken coop that was the same size and condition of those I had nurtured inside. Clearly, they don't need my nurturing, as this one was growing in some very hard packed clay soil, though it was getting some good nutrients leaching from the coop.
So, I'm going to bury a rotten tomato from each plant right next to that plant at the end of the season and cover that soil with wood chips. Come spring I will rake back those chips and see what comes up. Same with the squash, taters, sweet onions, peppers, lettuce, spinach, radishes, carrots, and even corn will be planted in the fall, covered over and then uncovered in the spring to let grow as they can and to see if it can be done. I've had volunteers from a lot of these in the past except the onions, but I plan to order the seeds themselves to plant this fall so that I'll get an early growth of sweet onions in the spring.
I've already got row markers on hand so I can label the rows and where they are so I can tell where to uncover in the spring.