I don't know who I love more today: your nephew or your mom.
I'm kind of thinking the same thing as golfwidow. The story of your mom is absolutely hysterical, but the idea that anyone, especially a child under 3, is obsessed with Rutherford B. Hayes is awesome. (It could only be more awesome if it were Chester A. Arthur, because instead of the beard, he's got the awesome mutton chop/moustache combo going.)
Ha! Yeah, my family is something else. And I think I'm gonna encourage that whole Chester B. Arthur idea! My mom told me yesterday that he has memorized the names of every single president and can now identify them all from their picture.