If you want to find colonials and such, you need to focus on just that. There are a few people on Tnet that hunt almost exclusively for old colonial coins...and do fairly well at it. I should add they are on the eastern half of the states and you are in a good area in Va.
These guys seem to hit the really old homesites. LOTS and LOTS of research...but seeing their finds....very well worth it. I hunt almost exclusively the areas where the latest history is mid 1800's. Don't make tons of finds...more like tons of unidentifiable trash...lol....but when I find that colonial....I'm gonna be pretty darn excited.
And I also want to say...you probably aren't gonna kick up anything like that in city parks. Those guys are usually at the back edge of someones farm or in the middle of the woods where a property vanished a long time ago.
My best advice...hone your map reading skills...learn how to do map layovers on google earth....go to the library and find the really old historical newspapers or property holdings, old census records...etc....usually on micro-filtch.
Learn to love local history.
Al