In Texas, sites that date from the late 1840s and 1850s give you ceramic
dates in the 1800-1830 range because everybody brought old stuff with them
to settle in Texas. We've joked that somewhere in St. Louis or on the east
coast there were stores selling "Pioneer Texas!" supplies, including 40 or
50 year old household ceramic sets in cases. Looks like we weren't far
wrong.
Jake.