Thanks for your information. I live in San Francisco, so my access to records in Ireland is limited. I've sent an email to the Quaker Library in Dublin requesting their assistance or advice, but I have not received a response yet.
I have a copy of the marriage registration for Elizabeth Crewdson Brown to Christopher Bolland Powell in the Parish Church in Aughnamullen on 27 April 1854. From this certificate, I know that Elizabeth's father was George Brown. Elizabeth died in Bury St Edmunds in 1873 aged 39, so she was born about 1834. The 1871 England census shows her birth place as Drogheda, and a family tree from the 1890s shows her father as George Brown of Drogheda and Gainsborough, Lincolnshire.
I am trying to find out anything about Elizabeth's birth and any information about her parents.