and we do suck up :P

Although that would really just make us more powerful by giving us ten senators instead of just two. ;-)

Parts of the former Republic of Texas are now included in the states of New Mexico, Oklahoma, Kansas, Colorado, and Wyoming.

California succeeded from the Union during the Civil War, and in theory governed itself. Although at the time nobody really cared.

And, of course, Hawaii was a free standing monarchy.

But other than that, yeah, Texas has always acted like its own nation ;)