This is the first in a series of "Histories of things" taken from a very tongue in cheek point of view.
The history of the Sweet Potato:
750 BC an unknown Peruvian digs up a root and starts gnawing on it. Sweet Potatoes become a big hit spawning massive population growth, a couple of ruthless rulers, a box with a diseased feather and some really unruly metal clad illegal immigrants who have very little respect for local customs of ownership but I'm getting ahead of myself.
A man from Italy wants to go boating but doesn't have the means to purchase one so he turns to begging which proves successful. He immediately gets lost in his new boat and about a month later runs it into a mound of dirt. Hungry he digs up a root and gnaws on it to much delight.
The local Taino people who were of course overjoyed to have been finally discovered told the Italian boater that the root was called batatas.
Not having heard of a batatas and having a slight hearing and/or comprehension problem he erroneously called it patata (you know from the rhyme potato, patata). Since the nice couple who loaned him their boat were Spanish this became the Spanish name for batatas.
Later the English not paying much attention to anything on the stranded side of the English Channel renamed it potato. Keep in mind there wasn't such a thing yet so you have to give them some credit for their originality.
One hundred years later another man (who due to his lack of accomplishments remains unknown) dug up another root in South Columbia (I mean America, don't get me started) drags another tuber back to Europe. It resembled the batatas but generally lacked flavor or any other discernible value so it was given to the Irish and also named potato.
Since people then named things by shape nobody noticed that the tasty batatas and the untasty potatoes were not in fact related nor did it matter - they were similar in shape so too should be similar in name.
One hundred years later some well meaning folks needed to get some shit done and since it was a bit early in the timeline to run by Home Depot for good hard working laborers they asked the Portuguese if they knew of anyone who might want a job where pay wasn't an object. They did and offered to provide the transportation.
The newly arrived people were famished and upon taking into their sight the aforementioned roots responded with the Wolof word "nyam" loosely translated as "If you don't give me something to eat I'm going to open up a can of Chris Rock on you". As a side note the same people used to say nyam back home followed by feverish gnawing on roots as well. Food is once again named by shape. Do not confuse nyam with Miami which although has a similar amount of dirt and clingy things attached to it differs in shape on the southern end.
Zoom forward another 100 years (thankfully history happens in nice round numbers) to the deep south when orange colored sweet potatoes were introduced. The folks there didn't want to confuse anyone by competing fairly so they decided to rename orange sweet potatoes to "If you don't give me something to eat I'm going to open a can of Chris Rock on you" but that was voted down in favor of Yam, an Anglicized version of the Wolof word nyam. Miami doesn't factor in here so we'll skip it for now.
Fast forward to another nice round number in history and you have the USDA whom with good intentions tries to rectify the naming situation and passes regulations to force everyone to put the name Sweet Potato on every box of Yams. They failed to define the size of the text thus a new industry was born for super small typesetters.