Is it possible to get a life insurance for my son's father...... we are not legally married. my son would be the beneficiary..

Without the father knowing about it? I don't think many (if any) insurance companies would do that since physicals and/or bloodwork are usually a requirement. Might work if you want to sign him for life insurance through the company you work for (I could do that when I worked...never did, but could have, and I really don't think a physical or bloodwork would have been needed).

he can take out life insurance and make anyone he wants to the beneficiary.

Yes, and no. He can get a life insurance policy. You can get a life insurance policy with his permission. But you can't put a minor on as the payee. If you do they won't pay until the kid turns 18 or 21 depending on the state and the company. That isn't what you want. You want it to pay you for the child's benefit.

Oh and to address the not married part. I knew an old lady who had a policy on her neighbor who had no family left. It was to cover the funeral. You don't have to be related as long as you have the person's permission.

I have one on my ex. You have to have an interest in their life to get it. For me it's that we have a child together

Wow I have not idea. My ex has an insurance policy on himself for my daughter as the sole beneficiary. It was part of the divorce agreement and is imbedded in the parenting plan so it is harder to get overturned.