You will need your birth certificate and ID. You cannot handle it at your local probate court. The estate will have to be opened in CA where your Uncle resided. There is a small estate affidavit you can probably use located here:
http://www.saclaw.lib.ca.us/Uploads/files/forms/AffidavitCollectionOfPersonalProperty_08.pdf
Call the probate court in his county and the clerk can forward to you any forms that you need.
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But is it an estate in Mass.? If his residence was in CA and that is the address on the account, it is not an estate in Mass. You can try it but I don't think it will work unless you can get the address changed.
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