Hi, Flummy!
If you're in zone 5, I'm not sure you're close enough to MD for a day trip... The spring swap is a plant swap, and this year it's at my place in Frederick
Our next mid-Atlantic seed swap will be in late January or early February, 2017. We meet in person at a buffet in Frederick, MD.
Don't overlook clover if you're trying to green up a spot quickly, especially if it's in sun. I've planted the deeper-rooted red clover and really enjoyed it, and I've also used white clover as a green mulch between garden rows. You can get seed in quantity, cheaply, from places like Tractor Supply and Southern States.
You may want to check out the plant and seed trading forum here at NGA / ATP.
http://garden.org/forums/view/...
Happy Spring!