Here's a close-up of the marking "EH3" and what appears to be a gavel -- it could be a snow shovel, but I'm going with gavel. Eric still won't say anything about the unit they were made for, and I haven't been able to find anything online:
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I was talking with another Marine and we figured EH is the tail code for a an aircraft squadron. So, we did a quick google search and came up with "Black Knights" helicopter squadron. They are a squadron of Osprey tiltrotor birds.
Here is an image from Vietnam with the tail code before they converted to Osprey.
I don't have any friends in an actual wing unit nor have I ever been attached to one. But this is my best guess. The 3 in the logo would probably designate some sub-unit designator.
http://en.wikipedia.org/wiki/VMM-264