Volunteers in the Garden

No, I am not talking about Woofers although some help might be nice at times. Tomatoes! My best tomatoes this year seem to be the volunteer ones. I am wondering if I should pay attention to when volunteers sprout and then plant. Also, I should note the soil and water where the volunteers spring up. They must like the conditions and so I should emulate them in the yard where I plan to actually plant tomatoes.