Problem with broccoli flowering too early by: Megan
Yes unfortunately your broccoli is going to seed if it has yellow flowers on it. The reason plants flower and go to seed too early is usually because they've been starved. Poor little things! Either they have not had enough water or not enough food, so they decide that it's no use trying to form nice big broccoli heads and instead they rapidly going into breeding mode and produce flowers, then seeds.
Another possibility, especially with broccoli which is cold loving, is that it's just too darn hot for your plants. Check your seed packet and see if it's a suitable variety for where you live. Most broccoli in hot areas like to be sown or planted in autumn so they can get established and produce during winter or early spring.