Hello, and welcome to WikiTree!
A little more information is needed about Elizabeth Lamb and spouse Isaac Brown to do a good search.
When and where did they live? If they were already married and living somewhere in the US for the 1940 census enumeration, we can start there.
If you put everything you know in a profile of each person, then everyone could help you look. If these folks are still alive, you should consider their privacy.
Please let us know more. -NGP