We don't have bulk trash days, but I can imagine it would be tempting. Personally, I would go ahead and rescue things, leave them in the vehicle and take them directly to the thrift store the next day. While it's good to think people might use the thrift stores or Freecycle if they know about them, Freecyle can be a pain to deal with where I live. Since we have no pick-up for large stuff, everyone's garages are just crammed full.
Having financial goals also really helps to cut down on the shopping, even at garage sales or thrift stores. Money not spent there can be used for other things. If you know where you are headed financially, it's much easier to stay on track.
Do not feel guilty about giving away gifts. It would be nice if all grandparents would value a savings account more than Wal-Mart junk, but remember that this is your home and you get to decide what resides there. When I work with clients, we play the real estate game. Take what your house would sell for right now. I like easy math, so we say a 2,000 sq. ft. house would sell for $200,000. That means that each square foot is $100 for storage. That's some expensive storage! Make it count. That's great for items you love and use. It's a total waste of space for old newspapers and junk toys.
The more you declutter the more your "mental" will change. I now view fiction books as consumables. I usually pick up paperbacks at thrift stores and as soon as I'm done, I pass them to a friend or put them back in my thrift store bags. I have about 5 fiction books I keep. I call them my warm and fuzzy friends and I read them every couple of years when I'm feel blue. Otherwise, my books are gardening books, quilt books, etc. and I go through those every couple of years. If I haven't looked at them, or they aren't ones regarding antique quilts, then out they go.
As the family declutters, be sure you set boundaries with other family members. Our home runs on the private vs public spaces theory. The public spaces (kitchen, living room, hallways, shared closets, main bathroom, dining room) may not be used for any type of personal storage. We each have a room, so my kids can keep what they want, but it must stay in their space. Since their space also has defined uses (floor for walking on, chair for sitting, bed for sleeping) the clutter they collect cannot interfere with the uses in the room. When the floor starts getting piled on, they know we need to declutter and they make pretty good choices as to what goes and what stays. I have lots of little boy junk coming into the house. What is it with rocks, sticks and rubberbands? I just remind them they must keep it in their space and how much of their space do they want to give up for that item? My kids also participate in what I call a "room zoom." Every evening we pick up for just a few minutes. After they've hauled something back to their room a dozen times they aren't always so thrilled about keeping it. It also reinforces how great the house looks when it's picked up. After the room zoom, we grab a bedtime snack and head to bed.
Take the time you previously used for clutter collecting and use it for fun. This doesn't have to cost anything. Find a like minded mom and set up a contest. Do the curb shopping together and see who can spot the funniest thing. Make it a contest and keep score. After a few months, the winner is treated to lunch at the loser's house. You could even curb shop for causes. My son's Scout troop has a yearly garage sale. If someone has the storage for items, they could be used for a specific purpose. Just don't allow each other to keep anything and make sure it gets dropped off. Or list it all on Freecycle the next day. The buddy system works for clutter control just like it does for dieting or exercise. I still like finding a good deal or something neat, I just don't let it overrun my space. Going with a friend to the thrift store hold me accountable not to just randomly buy stuff.
Set up a "pass it along" group for a few friends. Meet every couple of weeks and bring your magazines, books and any kids clothing that someone could use. This does allow for a bit of guilt-free getting of stuff which can later go in your thrift store bag. You can grab a magazine to read or a new book. The hostess is responsible for getting items not wanted to the donation center.
Always have a set place for give away. The easier it is to process the clutter the more likely you will be to follow through. I have a basket with a large bag on each level of my house. Everyone in the house now knows to just put things in there. I don't keep it in a hard to get to place like the garage. I'm too lazy to take all of those steps. When the charity calls, I always say yes, mark it on my calendar and then just go collect the bags and put them out. I do track the donations with ItsDeductible and we usually take around $5,000 in non-cash donation deducations. It only takes a few hours a year to track stuff and at our tax rate, that's some real decent pay! A great motivator, too.
If all else fails, block eBay from your computer. Make sure you go no mail for Freecycle. Play games with yourself. Put a star on your calendar for every day you didn't bring additional clutter into the house.