Moving is stressful. And stress can cause forgetfulness, which leads to new homeowners finding very strange things left behind in their new home, from dead cats to adult diapers or, if you're very lucky, cash.
It's a relief to clear all that packing material out of your new home once you're finally settled in. Those supplies don't simply disappear when they're out of sight, however. They have to go somewhere, and often that "somewhere" is a landfill.
Right now is a great time of year to declutter and donate. You might be digging into closets for holiday décor only to be shocked--disgusted--by how much stuff you've accumulated over the years. I always recommend decluttering and donating for a less stressful move.