There is also some discussion of this in John Vlach's Afro American Decorative Arts book, including good photos.

 As Pat Garrow said, John Combes' article in the Conference on Hist Sites Arch papers is the first archaeological mention, and is actually an excellent example of early historical archaeology.
 

Combes, John	
1972	Ethnography, Archaeology, andBurial Practices Among Coastal South Carolina Blacks. Conference onHistoric Sites Archaeology Papers, 1972, Vol. 7, pp. 52 - 61
Stan South may have copies available or get a pdf at: http://scholarcommons.sc.edu/archanth_historic_site_arch_conf_papers/

This late 19th c account is the first mention in print that I know of, but it is far from the only one. 

Decoration of Graves of Negroes in South Carolina
Author(s): H. Carrington Bolton
Source: The Journal of American Folklore, Vol. 4, No. 14 (Jul. - Sep., 1891), p. 214
DECORATION OF GRAVES OF NEGROES IN SOUTH
CAROLINA.
DURING a recent sojourn in Columbia, S. C., my attention was
directed to the cemetery for the poorer negroes. It is situated on
the edge of the town, overlooking the Congaree; the numerous
graves are decorated with a variety of objects, sometimes arranged
with careful symmetry, but more often placed around the margins
without regard to order. These objects include oyster-shells, white
pebbles, fragments of crockery of every description, glass bottles,
and nondescript bric-a-brac of a cheap sort, - all more or less broken
and useless. The large number of medicine bottles on some graves
has suggested that the bottles once held the medicines that killed
the patients.
Inquiry of residents as to the origin and significance of this custom
elicited no satisfactory explanation, and I was in doubt until the
April number of the "Century" reached me. In Mr. E. J. Glave's
article, "Fetishism in Congo Land," there is an engraving of the
grave of a Congo chieftain that would do very well for the picture
of one in the Potters' Field, Columbia, S. C. The author writes of
this grave: "The natives mark the final resting-places of their
friends by ornamenting their graves with crockery, empty bottles,
old cooking-pots, etc., all of which articles are rendered useless by
being cracked, or perforated with holes. Were this precaution not
taken, the grotesque decorations would be stolen."
The negroes of South Carolina are simply following the customs
of their savage ancestors, and are unwittingly perpetuating the fetishism
so deeply impressed. Some of the negroes on the coast islands
still preserve an imperfect knowledge of the native dialects of their
forefathers, and in decorating the graves of the departed they afford
an illustration of the long survival of customs the meaning of which
has been quite forgotten by those practising them.
H. Carrington Bolton.

There is a similar article that appears a year or so later, but I can't find the pdf. Its on Jstore however.
Ingersoll, Ernest.1892. “Decoration of Negro Graves.” Journal of AmericanFolk-Lore 5(16):68-9.

It is interesting that modern scholars still think of this practice in essentially the same terms...

Anyway, one thing to be careful of is to assume that this is some sort of universal practice, and that it means the same thing everywhere and at all times. 

In Georgia Ray Crook and Nick Honerkamp have completed a paper for SEAC that should be in print soon. Might contact Nick...

In South Carolina Christina Brooks (Winthrop U) has been working on African American cemeteries, and may be able to help.



Carl Steen



-----Original Message-----
From: Manning, Mary C <[log in to unmask]>
To: HISTARCH <[log in to unmask]>
Sent: Sat, Mar 24, 2012 7:39 am
Subject: Re: Ritual deposits on African-American graves


There is a brief discussion of Kongo and African American grave deposits in 
Robert Farris Thompson's "Flash of the Spirit" (1984) which might be of some 
help. I believe he documents the practice in the U.S. back at least as far as 
the early 19th century. See pp. 132-142.

Chris

M. Chris Manning, MSHP
MA Candidate, Dept. of Anthropology
Ball State University
[log in to unmask]
http://ballstate.academia.edu/ChrisManningPratt
________________________________________

Date:    Fri, 23 Mar 2012 17:14:16 -0400
From:    "Lyle E. Browning" <[log in to unmask]>
Subject: Ritual deposits on African-American graves

I am working on a burial permit for a somewhat problematical graveyard 
containing 60-100 people in Southside VA. The earliest land ownership is in the 
1770's with the last of the family out of the area by 1828. The marked graves 
have fieldstone headers and some footers. The presumption is that they are 
African-American slaves and descendants who were buried from the 1770's up to a 
totally unknown date, presumably well after the Civil War based upon the number 
of counted burials and the possibility of more that were not discernible as 
surface depressions.

Some African-American graveyards have produced what can for once be correctly 
termed "ritual" deposits consisting of items placed in memory of the departed, 
glassware and other objects.

My question is when this started? The earliest I have seen is solarized glass on 
a SC graveyard with objects up to the 1940's when the area became off-limits due 
to ownership.

Some of the very much later objects were in trees and some were also obviously 
surface deposits which has implications for the top 6 inches of soil in the 
graveyard in question.

Any information would be gratefully received.

Thanks,

Lyle Browning, RPA