boiled peanuts? do you mean peanuts in brine? I like peanuts in brine, hot or cold.
The best peanut soup, IMO, is from a restaurant in Williamsburg called the King's Arm Tavern.
You can get it at the restaurant, of course, but you can also purchase the soup in a jar at most of the colonial williamsburg stores.
I purchased a few jars about three, maybe four years ago, and learned that a couple spices which are added as finishers to the soup at the restaurant are not in the jarred version. So it took me some time at home, to figure out which spices to add... and since it was three or four years ago, I can't remember what spices I finally used. I know I added pepper and maybe paprika, some salt for sure, but that's all I remember.
My suggestion is to order the soup at king's arm tavern for lunch or something, and either ask the server, or try to figure it out on your own.
If you get the answer, be sure to post it here.
I'm guessing it was available at Mt. Vernon because George Washington was known to order peanut soup in Williamsburg.