RidgeRunner,
Have you examined the pdf documents of the original accession data? This is missing in many of the newest accessions, but the older ones often have critical details, such as where the seed was collected, only in the accession document. This info is not searchable in their clunky database, since some lazy folks (over the decades) entered "Washington, DC" as the source for many foreign accessions. As an example:
PI 112131 (
http://www.ars-grin.gov/cgi-bin/npgs/acc/display.pl?1129621) is an unnamed seed from Washington. But when you click on "Original plant inventory data (.pdf)", you find the following:
"112126 to 112194. NICOTIAN A TABACUM L. Solanaceae. Tobacco.
From Mexico. Seeds collected by W. A. Archer, Bureau of Plant Industry. Received September 13, 1935.
Introduced for Department specialists.
112126 to 112128. Bonanza.
112126. No. 3438. Collected August 23, 1935, at Santiago Ixcuintla, Nayarit.
112127. No. 3443. Collected August 24, 1935, at El Nuevo, Nayarit.
112128. No. 3456. Collected August 31, 1935, at Santiago Ixcuintla, Nayarit.
112129. No. 3445. Burley huero. Collected August 24, 1935, at El Nuevo, Nayarit.
112130. No. 3447. Burley negro. Collected August 24, 1935, at El Nuevo, Nayarit.
112131. No. 3458. Cash. Collected August 31, 1935, at Santiago Ixcuintla, Nayarit."
And the list goes on.
If you look at PI 404935, the Genetics and Germplasm Institute, in Beltsville, MD, has donated seed that it says is from "Cuba," but with only that description in the .pdf file.
PI 404951 says it's from Cuba on the detail page, but a look at the accession document (.pdf) indicates "No source data." Very messy stuff.
The only way I know of to locate accessions from Cuba is to examine every accession. If a different source country is indicated, then skip it. If only a source in the US is indicated, then check to see if there is an accession document (.pdf) for that entry. Others indicate only a volume of the accession document, whereas still others have no further info. If only a volume is indicated (There are well over 200 volumes, and some of these are broken into multiple parts, each weighing in at 50+ MB), then you have to go to
http://www.ars-grin.gov/npgs/pi_books/scans/vol.html and find the volume, often a hit-or-miss proposition. Once enough of the volume has downloaded, then you can search it for the PI number. It's all extremely tedious.
At one point, I was assembling a new database with all the missing and corrupted data clarified, but became terminally frustrated, and gave up.
So...yes, there are accessions from Cuba. You just have to find them.
Bob
EDIT:
Here are some for starters. They list Cuba as "geocty":
pi 404935 ? Primitive
pi 404951 ? Cigar Filler
pi 405643 'Coroja'. Cuba. Oriental
pi 405645 'No. 6055' Cuba. Oriental
pi 405646 'Criollo'. Cuba. Oriental
pi 405667 'Remedios'. South America. Oriental
pi 405668 'Vuelta (Abajo)'. South America. Oriental
pi 405669 'Little Cuba'. South America. Primitive
pi 408943 'Big Cuban'. United States. ?