The second page is pretty hard to make out, so here's what it says:
I hereby certify that the within named couple were joined together in marriage by me this 7th day of April 1827. Given under my hand + seal this 22nd day of May 1827. Thomas Allen.John, Jane and their family moved to Keokuk County, Iowa, sometime between 1840 and 1850, where John was listed as a blacksmith in the 1850 US census, and a miller in the 1860 census. Sometime between 1860 and 1870, they moved to Mercer County, Missouri, where John was a merchant.
They had five children, including my 3rd great grandmother, Nancy Garriott Brittain. Jane died in Mercer County, Missouri, on July 31, 1874. John died there on January 15, 1882.