I'm adding a herb. With great caution. Please note that this is for extreme pain and that is subjective to the person and please use this as intended and no other reason.

Papaver somniferum (Poppy Flower)

This is the plant that opium comes from.

This is a completely legal (and beautiful) flower in the U.S. You can purchase the pods from flower shops as ornamentals. Get only dried plant/pods not any that are treated. Treated ones are useless so avoid them. I don't know a thing about planting, but harvest prior to the bloom when it still in pod form at the stem and dry it. Keep the seeds for next harvest.

To use this as a medicinal herb you will be needing to make a tea. To make the tea you need the pods only. If there are seeds in the pods, remove them. Crush the pods using a coffee grinder or if that isn't available a heavy hand and a big knife to chop into small pieces. 1-3 pods per person at 2 grams each is what you should be aiming for. But it's a plant so this will vary and adjust accordingly. You will then put the crushed pods. For every 3 pods you will need a cup of water. Boil water. Do this briefly. Remove from heat and allow to cool. Then strain with a mesh filter of some kind, strain into another container. This liquid that is going to be used for pain relief. The 'sludge' you will put aside for a second steeping at a later time. It will be weaker but still potent. The pods strained will have some globs in it, don't worry that can safely be drank. This tea is very bitter. Consider using a spiced tea added to it to offset this. The rule for this is 'low and slow'. Low 'dosage' and very slowly. Each person is different based on weight, height, age and tolerance. Most people after a few sips feel the pain relief. If they say they're tired take away the tea. This is for pain, extreme insomnia, reduce severe coughing, stomach spams.

I will state I have never used this personally but was given this 'recipe' by a very old woman who never been to a doctor's office in all her life and wanted to keep it that way. As a disclaimer, this being an opiate it definately can be addictive. The rule in medicine is using an opiate for 5-14 days causes physical addiction, anything after that may cause a psychological addiction. This 'rule' is completely thrown out when it comes to chronic pain management. Use this accordingly and with your intellect. And know the person your making this tea for, are they former addicts or have those tendencies? Then perhaps do not offer this for them.