LFS Philly area (from closest to airport to furthest):
Aquarium World, Boothwyn, PA (knowlegeable staff)
Seven Seas, Brookhaven, PA (so-so)
Greenbank Aquarium, Wilmington, DE
Captain Nemo's (now Natural Pets), Norristown, PA (hit or miss)
If you're going to "hunt" for wood - you can try any number of the numerous creeks - Wissahickon, Darby, Chester, Pocopson
Also the Brandywine Valley is very nice country and the Brandywine River runs all along through it.
Note, I'm keeping you out of Philly "proper" as you'd probably want something that's been in clean streams (less pollution as possible - Philly is a big city)