Q.Tall (3-4) Ft Tall Cilantro With Hairy Thin Leaves.
It has the white cilantro flowers and it smells like cilantro. Can we eat this plant? The roots are big!

Certified GKH Gardening Expert
Once the plant has bolted (flowered and gone to seed) it rapidly loses flavor and is not worth harvesting. It's best to grow cilantro in spring and fall when the weather is cooler. Or you can plant in succession so you always have fresh growth.
If you are saying you didn't plant it, and you discovered it growing, I do not recommend eating it. Besides the reasons above, it may be a toxic look-alike plant.
Here is more:
https://www.gardeningknowhow.com/edible/herbs/cilantro/cilantro-bolting.htm
https://www.gardeningknowhow.com/edible/herbs/cilantro/tips-for-growing-cilantro.htm