You sound like me!! For the record, the Dollar Spot at Target was my Achilles' Heel! Here are some of the solutions I have found for my issues:
-if I check the mail, I immediately toss all junk into the outdoor recycling bin on the side of the house - never enters the house; if the kids check the mail, as soon as they bring it to me, I go through everything. I make a stack of filing stuff and usually once a week I will go to the desk in the basement and file away (we do not get too much that needs filing, so not too big of a pile)
-we just started homeschooling this year, so with a 15-mo old, 6-yr old, and 8-yr old, I neither have the time nor the patience to shop...it has reduced our bills and clutter SO MUCH!
-I try to regularly go through clothes, knick-knacks, etc. and weed out those things we have not used in 6 months to a year. I seek opportunities to find great homes for these things (i.e., local fire this week left several families without anything, so it was the perfect time to go through, find clothes, housewares, etc. that could be better used elsewhere)
-with schoolwork (when both kiddos were in traditional school especially), I would keep the tests, essays, projects, pictures, etc. that showed progress, that were special, or that I felt drawn to keeping. I still kept a ton, so at the end of each semester, I would weed things out again, and by the end of the year, it was much easier with perspective to keep things that would be special down the road. I had a clear, portable file box in which to store it all, then at the end of each year, added the "keep" pile to a manilla folder (one per child) that now sits in my files. Not the best, but it got the tons of papers out of my junk drawer and off the kitchen island