If you hold only a British passport the only way to get a work visa is to be sponsored by a US company. There are also avenues for seeking employment in areas such as ski resorts etc. You might be best speaking to an immigration lawyer regarding a your offense. Possession and consumption of drugs are a big NO NO when it comes to US immigration but the possession of a implement may not be. I wasn't aware it was illegal to carry a drug implement in the UK. Did the implement contain signs of drug use?