The Hilton College of the University of Houston's Hospitality Industry Archives includes a wonderful selection of menus from the 1850s and 1860s.
They're great to read, but unfortunately, the college's archive makes it really difficult to get a decent downloadable version. This Imgur post has high-rez versions of many of these public domain documents.
One striking difference between these menus and contemporary ones is how much of the food came as prix fixe, often included with a hotel stay. Also noteworthy is the focus on booze as the major feature of any meal. My favorite among the docs is the Baltimore Barnum's City Hotel menu, which includes the train schedules and booze selection around the border, for handy reference.
1850s and 1860s Hotel and Restaurant Menus
[Hospitality Industry Archives/Hilton College of the University of Houston]