How do you teach appreciation?

Today was a day. I was trying to catch up on laundry. I was doing school clothes for my girls and was slowly realizing that they were missing a lot of clothes. I searched my house thinking they were folded and misplaced (which wasn't likely and you would know that if you knew my folding habits). I looked everywhere, so as a last resort I marched up to my girl's room to have a look. It looked clean and tidy, but I noticed one of my daughter's bed looked weird, kind of uneven. I picked up the bed skirt to look underneath and about had a heart attack, there was so much stuff piled up under there that the bed was starting to come off the floor. So wouldn't you guess I went over to the other bed and found the same thing. So for all these weeks I was thinking my wonderful daughters were doing such a good job at cleaning their room, boy was I wrong!! I got sooooo mad. I found tons of toys, dirty clothes, and garbage. It was like a mutant rat had moved in. I tore it all out and called them upstairs. The look on their faces was priceless. My younger daughter, let me just tell the truth, she's the narc. Don't ever commit a crime with her, she will rat you out in a second. She started in-It was K's idea...blah, blah, blah. And K was-no it was all S's idea and I had nothing to do with it. I was so mad I could just spit. I didn't think yelling would get my point across so I sent them both downstairs and I told them to get me a few big garbage bags. I started going through everything. I counted 27 barbies, 23 my little ponies, countless babies and accessories, books, dress up junk. Even things new in the box sitting there unplayed with from Christmas.
Due to our current financial situation, seeing all this in front of me knowing it was all barely touched or played with made me very distressed. The fact that these two children of mine don't value these things enough to even pick them up off of the floor, but rather casually stuff them in the corner or under a bed just because they are too lazy to take care of them or pick them up. I was mad, but I looked at that pile of barbies and I held one up. I told the girls: Somewhere there is a little girl with a hungry belly, she probably has nothing to eat tonight and she certainly doesn't have nice clothes or a barbie to play with. She probably doesn't even have shoes or a warm blanket to cover up with at night. But here you two are with 7 blankets laying on the floor and 27 barbies stuffed under your bed. I started crying, and so did they. I think I got my point across. So we are in the process of simplifying. We went through the barbies and I made them pick 5 to keep. The rest go in the bag and we are donating them. The ponies are all going. The unopened things, going. All but one or two of the blankets, going. And I even took down one of the beds, because they were using it to pile things on and sleeping together in the other one. I shared a bed with my sister until the day I moved out, it didn't kill me and it won't kill them. By the time I am done cleaning that room I will probably have 2 or 3 full 30 gallon bags of stuff to donate. It makes me ill that all this time I have spent worrying about if my kids will have enough, that I have taught them so very little. So today that all changes, we will have less so we can appreciate more. All that money spent we could have probably gone on a nice family vacation, but instead it's just stuff that gets stuffed under a bed. I decide today that the best gifts I can give my kids are good memories, memories can't be shoved under the bed. So today they are mad at me, but I hope in the long run that by giving them a little less I will be teaching them a little more.