Thanks for your comments. This stuff is still up there now, if you want to see it. Stand on the shady side of a building, move to where the sun is just blocked by the building, and adjust your binoculars until they come in to focus.
This stuff has been reported from north-eastern Dallas all the way to Corpus Christi (swampfx's post at #137). Don't know if these are localized pockets, or generally predominant for that range.
Has anyone heard any further details on the stuff in Trappe, MD, other than it was determined to be 'harmless'?
It was bird s***, as I noted earlier. The stupidity of some of the residents of the Eastern Shore is beyond comprehension.
Cottonwood does it's thing Feb-March.