Judging by some of my former neighbors' yards, I don't think your husband is alone in this compulsion. From what I've read about hoarding, it falls in the obsessive-compulsive disorder spectrum.
Some links that might be helpful or informative:
http://www.ocfoundation.org/hoarding/tre...ve-hoarding.phphttp://understanding_ocd.tripod.com/hoarding.htmlhttp://www.bio-behavioral.com/hoarding.aspThere are also Yahoo support groups for this issue. You might consider consulting some other spouses in similar situations for unique strategies on how to cope.
Sounds like it's going to require psychological intervention to resolve in any event, but one article acknowledges this is a particularly difficult affliction to treat due to most patients' reluctance to acknowledge there is a problem.
If hubby ignores your pleas for help, see if you can get a family member or close friend of his to intervene and persuade him to at least consider MC counseling so you two can learn to deal with conflict more constructively. Even if it's under the guise of "regular" MC, if you can at least get him in the door with you to see a counselor, then when you are both there you can casually bring this issue up in front of the counselor.
But rather than stating, "We need to see a counselor about YOUR hoarding problem, honey," take a different and less threatening approach such as "Dear, I think WE need to learn how to resolve conflict more effectively. Maybe a counselor could help us." This removes blame/pressure and should make him less defensive from the outset.
Good luck.
~Silverwraith