I live in a pretty generic suburban area, but much of the housing in my neighborhood was built in the 50s and 60s, and it seems that they weren't so keen on destroying all of the natural environment back then. As a result, there are a lot of wooded areas and a number of small streams that cut through Coastal Plain sediments and drain into the Potomac. A geologic map of the area calls the deposits "Qte: Low-level fluvial and estuarine deposits (Pleistocene)." Mainly, it's a lot of sand with pebble-to-cobble sized clasts and lots of of iron oxide chunks - overlain, naturally, by every polymorph of poison ivy conceived of by nature. It's an area I'm familiar with, having spent a great deal of time there when I was young, getting mucky and probably exposing myself to any number of diseases and bacteria (I didn't actually go IN the stream, but even with wading boots, it's hard to avoid getting a little wet. Hooray for rubbing alcohol and soap.)
The streams themselves are supposedly spring-fed, and there are a few roads and subdivisions with "Springs" in the name. I suspect more water comes from runoff these days, since there are a lot of paved surfaces in the area, but I can vouch for the existence of the springs - one part of my yard and the sidewalk adjacent are constantly wet, no matter what the weather has been like, and none of the drains in our house connect to the sewers in that area. Wet enough, in fact, that's it's created a great example of differential erosion in the concrete curb where the water drains to the street.
Anyway, back to the rocks. Here are some of the clasts I picked up:
Antietam metasandstone: An old friend, and one I was expecting to find in abundance (which I did). Very distinctive Skolithos trace fossils (worm burrows), which make it pretty easy to spot. This is a Chilhowee Group rock
Sandstone with cross-stratification: Lots of this, surprisingly. The cross-stratification ranged from mm to cm-scale layers (in the largest cobble I picked up). I'm betting Chilhowee Group again, possibly Weverton (braided stream deposits) or another part of the Antietam.
Anthracite coal: No photos of this, but I'm sure everyone can guess what it looks like. I was a bit surprised to find it, as this particular stream doesn't run anywhere near railroad tracks, which is usually where I find stray coal in my area. I have doubts that it would have survived the trip from western Virginia to the Coastal Plain, so I don't think it arrived here naturally. Perhaps it was dumped or washed in from someone's yard - the land around my house used to be part of a large farm, so maybe it's historic coal.
I really want to show off the cross-bedding in the large cobble I collected, but I haven't had a chance to clean it properly just yet. I've also found a few other samples that I'm not completely sure of, but again, haven't had time to sit down with the handlens and camera, so they'll have to wait until the weekend.
Some good resources for Virginia geology:
USGS Geolex Database: This is a great website - it allows you to look up recognized geologic units by age, name, location (down to the county level), rock type, even by author citation. Units are displayed with alternate names, "areal extent", type localities, subunits, and a history of the names and descriptions that have been applied to the unit, even back into the 19th century, with the authors and publications they're found in.
Geology of Virginia (College of William & Mary): A very good basic overview of Virginia geology, with generalized province and geologic maps to download, and a selection of outcrop and sample photos.
Geological Evolution of Virginia and the Mid-Atlantic Region (JMU): Oddly organized, in my opinion, but useful for quick reference.
Virginia Department of Mines, Minerals and Energy, Division of Mineral Resources: Archived issues of the Virginia Minerals newsletter, some open-file reports, and a source for info on diamonds in Virginia.