Good stuff!
A favorite of my mom's (and me!), she worked in a deli in MA that sold this stuff: Usinger Natural Casing Braunschweiger.
"Using Fred Usinger?s old world recipe?this has been our specialty since 1880. Generations have loved the incomparable taste of this delicately seasoned liver sausage with a creamy texture that is smoked just right. Our Braunschweiger with thinly sliced onion on rye is considered the perfect Milwaukee sandwich"
note - Usinger's does a lot of mail-order business!