In the US, you can post a wanted ad on Craigslist, or you can ask for chipped dishes on Freecycle and similar lists. Make sure that you say that you want these items for raw material to make stuff that you're planning to sell, if you're asking for people to give it to you for free.

Or as another person said, go to a thrift or second hand store. My advice is to tell a worker there that you are interested in things you can break up. It's quite likely that the shop has a collection of stuff that they haven't put on display, because it's chipped or otherwise unsuitable for sale. I make quilts, and I've asked about clothing that's too damaged to sell, and I've walked out of the store with about 20 pounds of cloth, and paid about $5 for it, because the shirts were ripped up and couldn't be worn...but there was plenty of good cloth there for someone who was willing to cut it up! The thrift shop gets to sell some stuff that they would otherwise have to throw out, and I get a lot of material that I otherwise would have had to pay over $250 for, so everyone wins.