What is the early recorded use of "white trash" and has its meaning changed over time?

Solution 1:

Personally, I've never heard "white trash". The text you quoted was by Grant, who lived in the 19th century. "White trash" came about in the 1830s:

The term white trash first came into common use in the 1830s as a pejorative used by house slaves against poor whites. In 1833 Fanny Kemble, an English actress visiting Georgia, noted in her journal: "The slaves themselves entertain the very highest contempt for white servants, whom they designate as 'poor white trash'"

...By 1855 the term had passed into common usage by upper class whites, and was common usage among all Southerners, regardless of race, throughout the rest of the 19th century.

And surprisingly, it seems to have retain most of its origin, although it is now sometimes used jokingly:

as in the humorous book The White Trash Mom Handbook: Embrace Your Inner Trailerpark, Forget Perfection, Resist Assimilation into the PTA, Stay Sane, and Keep Your Sense of Humor by Michelle Lamar and Molly Wendland (2008).

But mostly its still used to mean poverty:

Autobiographies sometimes mention white trash origins. Author Amber L. Hollibaugh says, "I grew up a mixed-race, white-trash girl in a country that considered me dangerous, corrupt, fascinating, exotic."

Solution 2:

I found a slightly earlier antedating to Thursagen's 1833 and simchona's 1831.

The 1824 A Winter in Washington: or, Memoirs of the Seymour Family, Volume 1 by Margaret Bayard Smith:

"Hold your tongue, Joseph ; do you think because I bemean'd myself to marry such a neger as you, I'll be beholden to them white trash, that with their hard hearted ways forced me to do the like? No, indeed ; if they could turn their own colour out to perish, no child of mine shall be beholden to them."

Solution 3:

Look a little further in Grant's Memoirs and the term comes up again (from CHAPTER XLI.):

There was no time during the rebellion when I did not think, and often say, that the South was more to be benefited by its defeat than the North. The latter had the people, the institutions, and the territory to make a great and prosperous nation. The former was burdened with an institution abhorrent to all civilized people not brought up under it, and one which degraded labor, kept it in ignorance, and enervated the governing class. With the outside world at war with this institution, they could not have extended their territory. The labor of the country was not skilled, nor allowed to become so. The whites could not toil without becoming degraded, and those who did were denominated "poor white trash."

So 'poor white trash' according to Grant meant white people who worked and did not have slaves to work for them. So apparently one could be a prosperous and hard working white farmer or some other type of laborer in the South and still be called 'poor white trash.'

Solution 4:

It looks like it’s been a term of derision from the start, originating in black American speech.

I found an earlier example than any of the other answers, from 1821 (coincidentally also the earliest attestation given by the OED, which updated its entry in 2015):

why do you lag behind? Come along and do not spend your precious time, in company too, and conversing with White Trash.

On hearing the phrase white trash as it was altogether new to me when taken in her sense, I seemed as if bitten by a gallnipper. [...] it was as natural for her to say White Trash as it would be for myself or any other of my colour to say Black Trash.

The Illinois Gazette (Shawnee-town, Illinois), [Saturday], [June 23, 1821]

I also found one from 1822:

A very novel and whimsical trial came on in our Circuit Court on Thursday last, Nancy Swann, a lady of color whose mighty powers of witchcraft have made "de black nigers, and de poor white trash" tremble, was indicted for practising in and upon one Peter Bolt [...]

Bangor Register (Bangor, Maine), Thursday, August 01, 1822