If you want to go there and you do not have a car and do not want to rent a car, you can go there by public train. Every year the State Railway of Thailand will organize trips to visit sunflower fields. You can check the detail from its website and you can call 1690 for more information. In the website, we will see other train trips as well, because the SRT organize both one-day trips and overnight trips all year round. I have never been to sunflower fields by train, but I have heard that you can see the sunflower fields from the train the views from the train are more beautiful than from the car. If you want to join the trip, I recommend you to book the ticket in advance because the trip is quite popular among local.