This picture is from Tattershall in Lincolnshire, England, where they boast of having Tom Thumb's house and grave. The famous T. Thumb here was about 18 inches tall. I wonder what the story was behind this.
There’s another story that he died at Lincoln and there was a blue flagstone (now lost) marking his grave in the Cathedral there. That's not too far away.
As far as the folktale itself goes: the earliest mention I could find of Tom Thumb is in 1579. The earliest print version (1621) claims that “little Tom of Wales, as big as a miller’s thumb” is a very old tale, older than Tam Lin (which dates at least to 1549). Just for reference, Tattershall’s eighteen-inch-tall T. Thumb would have been born in 1519.
Within the ballad, the most popular version of the tale - where Tom is a knight of King Arthur - there are no solid dates. Tom Thumb and Jack the Giant Slayer are both examples of later fairytales using the Arthurian mythos as a backdrop. The first existing mention of King Arthur dates to the year 830 and there are several theories as to who the character might have been originally based on.
Henry Altemus' edition of "The History of Tom Thumb," puts Tom's year of birth in 516. The version that adds two chapters, when Tom Thumb stays in Fairyland for two hundred years before returning to serve King Edgar (the Peaceful, I think - King from 959 to 975), placing his year of birth and the reign of King Arthur somewhere in the 700's.
There is one very different version, Tom Thumb’s Folio, or, A new penny play-thing for little giants, published in 1791. This one dates Tom’s birth to 1618, the year Sir Walter Raleigh died. It even gives us Tom’s birthday. In this version, a solar eclipse caused his small size, and there was a total eclipse on June 21. And he’s from Northumberland. (Ha ha ha.)
This website is based on my research into folklore.