Now THAT is a workable idea. TGSL, you want to ping the DC chapter to see if we can drum something up to arrange this?
A truckload of cheap concrete masonry bricks (I'm looking at "cost for message vs. payoff", not "actual bricks that can be used to build a wall" here) from Home Depot wouldn't be too expensive (I'll call up to the local one and get a general price quote for a pallete at lunch), and we could either rent a truck for $19.95/hr to deliver it (along with some banners with a poignant, yet typically polite, message), or we could pay to have them delivered...
How about Z-bricks. One of those will go in an envelope.
Instead of taking bricks to Washington, why couldn't citizens start heading down to the border and start building the wall ourselves? A convoy of dump trucks heading south would be sure to get some attention!