Harvest from summer to late fall. They can be cleaned by soaking to remove sp or boiling to glaze the sap. Often, walking through your neighborhood, you will find neighbors yards littered with them, and many times they won't mind A BIT if you help yourself to as many as you can take to avoid having to rake them. Forest lands are another wonderful source, but can be illegal, so its best to check with local forestry service before getting slapped with a lofty fine!
Gather in the early morning, immediately after low tide. They can be cleaned by burying 18 inches in the ground to kill any micoorganisms for one month, or by freezing or boiling them.
Gather feathers during molting season, beginning in the spring and lasting about six months. To clean found feathers, fill a bag with 1/2 cup flour, one cup corn meal, and three tablespoons borax, ( the borax acts as a dinfectant) your feathers and shake. Remove the feathers and shake out the excess cleaning mixture. Its best not to use soap and water, because the feathers contain natural oils that protect them.
Wallpaper stores often have sample books to get rid of that scrap-bookers or card makers or other mixed media artists could reuse.
Tiles for mosiacs can sometimes be collected for free by going tile shops and ask the owners for tiles left over from jobs and the owners are happy to comply because it keeps their trash removal costs low.
Often, home improvement or hardware stores have items that crafters can use that they just throw out and would happily give you, if you just ask.
Craigslist and online free-cycling networks simplify the search for furniture needing a facelift by connecting users. In some towns, Goodwill Industries has last chance stores for items that didn't sell, and price furniture in the five to ten dollar range.
Some free-cycling sites to try:
Visit local newspapers for left over papers for paper mache projects. Find out what they do with the newsprint that is left on the roll after the printing. Often times, the end rolls are given away or sold for next to nothing. A bonus is the sturdy cardboard tube that the paper comes on.
Cutting apart cast-off clothing at the seams is a time-honored tradition for reusing fabrics for scrap quilting and clothing for little people. I use a lot of vintage linens in my craft projects as well; so often I find beautifully intricate embroidered pieces with damage. I DESPISE throwing away vintage linens... I cut the damaged areas out and save the embroidered pieces for later use, guarantying me one-of-a-kind finished projects. This is another way I take advantage of Goodwill Last Chance Stores is by buying my vintage pieces there; because they can't be sold in there regular stores, they are sold by the pound, usually about a dollar each pound. I've bought insane quantities of vintage hankies and doilies and quilt tops for practically nothing. My town hosts the Ashland Shakespearean Festival, and they give away fabric scraps left over from costume making. Try contacting local tailors or seamstresses to see if they will give you their scraps.
Start by asking family and friends for any broken jewelry they may have, or scour thrift stores and yard sales for inexpensive jewelry; components like beads and clasps can be reused in new projects. Funky or vintage buttons can be taken from cast-off clothing items and add interest to your jewery. Make your own beads from paper.
Crystals and beads can be harvested from broken lamps. Feathers can be harvested during the spring, when birds are molting (be sure to clean them.)
There are many online resourses for free, public domain graphics for craft projects. Graphics Fairy (http://www.graphicsfairy-diy.com/) is my favorite, offering beautiful vintage images.
I've gotten pretty lucky asking local homesteaders for their fleece after sheering; apparently shearing is a huge endeavor, and by the time you get your sheep shorn, all the fleece has to be cleaned before it can be used or sold for crafting projects. Its very time consuming, but if you don't mind cleaning the wool, sometimes they will just give it to you to avoid doing it.
I know what you're thinking. Bike tubes? Why the H-E-double-hockey sticks would I craft with BIKE TUBES?
Oh, I'm so glad you asked. Bike tubes can be used to make all kinds of knarly/ manly/ eco-friendly good stuff! Belts, bags, door mats, juggling sticks, jewelry... you name it!
Inner tubes from bike tires can be collected by the boatload from bicycle repair shops. To prepare them for use, cut the valve portion of the tube with scissors, and then cut straight down the length of the tube until the tube opens up. Sometimes there will be a gross toxic looking sludge inside from a previous repair attempt, but it will easily rinse away without any scrubbing. The tube can then be hung to dry and then rolled up until needed and secured with either a rubber band or tape.