You shouldn't have to do this in a first world country, but:
* Go to the ER without ID
* (optional) Ask how much it will cost
* (optional) They do not give prices, as a matter of policy
* They must treat you by law
* Afterwards, offer a cash payment you deem reasonable
* They will accept or decline it
Transaction complete.
For non-emergency care and prescriptions, get cash quotes up front, pay in cash, and order discount online prescriptions from canada, a first world country.
For chronic medical conditions, leave the US and immigrate to a first world country.