How can I prove I'm entitled to my mom's estate without a will?

My mother has passed away but she never wrote a will and I am the only child she has. How do I prove that I am entitled to her estate? There are things like the insurance that are still in her name, along with checks that are sent out. I need to have these checks in my name so I can cash them but there is no will so I can not prove I am the executive of the will.