I should know but I don't. I rarely get to PF for yardsaling, but I think I heard it's generally the first Saturday of the month????
Not sure if it's free or not to sell. I'd probably just stop by and ask one of the sellers.
Calvert County Parks & Recs is holding an indoor yardsale at the Southern Comm. Center in Lusby on Sept. 6 and it's only $3 a space (bring your own table) or $7 if you want a table. It's nice since it's indoors, there are restrooms etc. I generally rent a space there but cannot this time around. But I will definitely be a shopper. If interested, you should stop by a Parks & Recs office since the fee has to be paid in advance.