Oh goodness no, I could never put them on cars. Like you ladies, I absolutely hate those as well

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I was trying to think of locations to put them. Maybe even a location to put a small stack of them. So far I'm thinking, our grocery stores and convenience stores both have announcement boards that you are allowed to put up flyers. Maybe putting a stack at the library?
As for signs and advertising, I already have big bright signs that I will put up the morning of and take down right after I'm done. They are simple but very bold and clear to read. I'll also put it in our local paper/shoppers to get some more people. As for freecycle/craigslist/websites, I live in a very rural area so those don't really cover me, but I might try anyways (what's it going to hurt?).
I was just wanting to see if some of you creative minds might know where else to put them. Oh and btw these are not standard postcard size. They are about the size of a half sheet of paper. Very colorful and have all the details of the yardsale on the front and back.