Looking for Information on Rapp of Illinois and Nebraska

I am looking for any/all information that you might have on Standish Rapp and his wife Louisa Dauwalter Rapp. Standish was born in Germany in/about 1851 and immigrated to America in/about 1857. His wife Louisa was born in Illinois in/about 1859 - her parents were both from Germany. I do not know the names of the parents for Standish or for Louisa. They later moved to Nebraska, where they lived until they passed away...