There is absolutely no reason to doubt that they wont fruit there again next year. You hovered up every single one that you saw but by the time you see them, the spores have flown and it has re-seeded itself. It is very obviously a strong and healthy organism that lives in the soil, so it will easily be able to withstand your picking for a year or five.
The way I do it, the way I think of it and the way I hope you do it is. Now you found that field, respect it. Next year, you know it is there so don't go back to it. You now know how to find them, so go out and look for another. Give it time to recover and build up your own personal data bank or resevoir of picking spots. Believe me, there is absolutely nothing remarkable about that field.
Jealously guard your finds, don't tell a single sole the locations. Most people are too lazy or too stupid to think for themselves. When word gets out about a place human nature being what it is, you soon end up with cars full of people turning up.
