Just to keep this post from being too boring, I offer you here "The Story of The Old Cannon":
Throughout the United States, the "Gonzales Flag" is more commonly referred to as the "Come and Take It Flag." It is a pervasive symbol of Second Amendment supporters, simple in both image and statement.
The history behind the flag, its relation to the Texas batle for independence, and the significance of the cannon itself can be found in various history books. For a brief overview, the Wikipedia entry on the Battle of Gonzales is a good starting point.
Somewhat lost to history, however, is that the flag was originally called "The Old Cannon Flag," in reference to the fact that the cannon itself had little military value, but stood as central icon that started the Texas war of independence, both literally and figuratively.
Noah Smithwick, whose personal accounts of the early history of Texas are detailed in his story, "The Evolution of a State," had this to say about the flag, "[It] consisted of a breadth of white cotton cloth about six feet long, in the center of which was painted in black a picture of the old cannon, above it a lone star and beneath it the words, 'Come and take it,' a challenge which was lost on the Mexicans. It was not called the Lone Star, however, but the Old Cannon flag."
The Old Cannon itself was supposedly recovered in the 1930s and is now displayed at the Gonzales Memorial Museum, pictured below.

It should be noted, however, that elements of the cannon pictured do not align with Noah Smithwick's personal account. Being a blacksmith, Noah's recollections should be taken seriously, and it's highly likely that the cannon pictured is not the original. By his personal account, "the old cannon was abandoned in disgrace at Sandy Creek before we got half way to San Antonio." Thus, an important part of both Texas and United States history may yet be lying, buried under layers of mud, somewhere along the shores of Sandy Creek.