I highly doubt that, if you live in California you can't accept Euros, silver for payment. If you could no one would use the dollar.
It's true. From the
treasury site:
The pertinent portion of law that applies to your question is the Coinage Act of 1965, specifically Section 31 U.S.C. 5103, entitled "Legal tender," which states: "United States coins and currency (including Federal reserve notes and circulating notes of Federal reserve banks and national banks) are legal tender for all debts, public charges, taxes, and dues."
...
This statute means that all United States money as identified above are a valid and legal offer of payment for debts when tendered to a creditor. There is, however, no Federal statute mandating that a private business, a person or an organization must accept currency or coins as for payment for goods and/or services.
Case law, however, does exist that basicly means that if US$ were offered in settlement of debts, but were rejected because of a contract that required some other form of settlement, any court will hold that debt as void.
So, in practice, any business that allows a customer to acrue a debt first (as an example, a sit-down resturant, where you eat first and pay on the way out) must accept US$ as payment of that debt, even if they had a huge sign on the way in that said, "No gold or silver, no service".
I've used this to my advantage in the past, as I don't use credit cards. I had reserved a particular tool from Home Depot's tool shop, and went in to rent the item. Advance reservation is free, unless you cancel, so they didn't ask for anything more than my name and address on the phone when I called. I went to pick it up, and they asked for a credit card for the security deposit. The clerk insisted that he couldn't rent me the tool without a credit card, and I said that I was certain that his computer system did have a cash deposit option in theer somewhere, because that was the law. He ended up calling his manager, and after going through the whole ting again, the manager called some kind of corporate office, who proceeded to tell him how to access that part of the POS system.
I left with the tool, and did not need a card despite their insistance that only a credit card was acceptable.