You may have nutgrass and don’t even know it. Definitely do not let it get this big with the seed heads. It is best to apply the Sedgehammer when there are only 2-3 leaves. By adding the surfactant, it will stick to the plant without having to let it get taller.
Don’t try to pull them out. They have tubers (nuts) underground that send off shoots so if you pull one out, you have simply broken off the connection to the next one that will definitely find its way to the surface! I have personally used this product with great results. It took a couple of years of diligent spraying but I don’t have the problem anymore.