When I was in DC at Arlington (OK, which is in Virginia, not DC, but still...), we happened to stumble on a wreath laying ceremony at the Tomb of the Unknown Soldier. It was right after the changing of the guards, actually, but long enough that many people had wandered off. The soldier who had been on duty went into a small guard shack off to the left and another soldier came out and removed a wreath that had been on a stand near the tomb. He placed it on the ground behind the tomb alonside a long row of similar wreaths. I don't tknow how often they change the wreaths, but there were quite a few there on the ground.
Then the guard returned with a new wreath and a trumpeter. He walked up the steps of the viewing area where some ladies were waiting. He spoke to them for a few moments, then they all marched together down the steps.
The ladies placed the wreath on the stand, then stood at attention as the trumpeter blew Taps.
Then they turned and walked back up the steps. I believe the wreath was dedicated to their mother, but I'm not sure. I'm sure it was quite an honor to be allowed to lay a wreath in such a prestigious place.