Finding free stuff that you can sell online or in a flea market is quite easy. Just be patient in walking around and you will surely discover loads of unwanted stuff and profit from them.  Here's how it works:
First, grab a local newspaper and search for ‘moving sales' in the classified section. Note them down and visit them. Don't forget to note down what they have and what they have left. Before leaving, make sure you hand a business card that says something like ‘We pick up Unwanted Reusable Things-Free!' Next, mail out a brief letter to the places you visited and state again, that you will take away all unwanted reusable items FREE.
As days pass by, they start to feel pressured. Remember, these people have a moving schedule to follow. So, if they still have lots of stuff left and receive your letter on time, then you get your share of business.
You will be expected to take away everything, even the less desirable things. In this case, you can still take the items you don't want and drop them off to a charity. You will be surprised with all the stuff that the owners are ready to give away-antiques, furniture, even pets. Nevertheless, be sensitive. You are handling stuff that may have a sentimental value to the owners. So, watch what you say about their items and take care of their property.