@SarahGen-- Oh yea, you don't want those guys hanging out on your lawn or garden. Before you know it, it will be everywhere and then you will have to hire a professional or use a ton of weed treatment to get rid of them.
Hawkweed is super hardy. It's almost impossible for it to die on its own. It's durable to harsh weather conditions and frost. The seeds can stay in the soil for a long time and germinate in spring.
While getting rid of it, make sure that you don't help distribute the seeds or more will come out. Put a bag over it before you pull it out. Don't allow the seeds to spread. They can even spread in air or on animals. If you get it under control now, you will save yourself a lot of trouble later.