Um, Mormon sources don't count. Do you have anything from a non-Mormon source.
The book of Mormon talks about horses, elephants, wheat, coinage, great towered cities, chariots, and the list can go on and on.
Or let's put it another way. The Nephite/Lamanite civilization lasted for about 1000 years.
The Roman Empire lasted about 1000 years.
With the Romans, we have dozens of Roman buildings, monuments, roads, coinage. We have references to them in all sorts of literary sources, not just the bible. We have remnants of Roman language (Latin) in modern languages today (Spanish, French, Italians, among others)
And for the Nephites? Nothing. Not one archeological site. Not one Native American language that appears to have derived from Hebrew. Not one coin with a Nephite ruler's face stamped on it.
Now the accounts from the BoM DO make sense if you put them in the context of their time. In the mid 19th century, people were digging up the remains of the Mound Building Civilizations in North America, and America, being racist as it was at the time, concluded their now way the Native Americans they were in the process of exterminating could have build such wonders. (In fact, the builders were wiped out by plagues brought by Europeans before white people got that far into the country). And as a result, you had a lot of theories about who could have been the REAL builders, and they HAD to be white people. So they theorized Vikings, Romans, and of course, Hebrews.
As far as the tales of elephants and horses? Largely drawn from archeological finds of mastodons and Dinohippus in North America without the context that they went extinct tens of thousand of years ago.
Heck, Joseph Smith wasn't even the first guy to come up with that goofy theory. You can thank the works of Rev. Ethan Smith (no relation) for that in "A View of the Hebrews", which Joseph Smith largely cribbed.
