Tablecloth Holder on Picnic Table

Instead of tablecloth weights consider using clothespins to hold your tablecloth. 

My significant other attached clothespins to the picnic table by first taking the clothespins apart then drilling a hole through the clothespin. Then he put a screw through the drilled hole and screwed the clothespin to the underside of the table. Then he reassembled the clothespin. Below is a pic before he reassembled the clothespin. 

I bought two tablecloths from Walmart and cut one to fit the top of the picnic table and the other one to fit the seats. 

I attached the tablecloths to the picnic table with the clothespins. You can use a lighter to burn off the frayed edges after cutting to that the cut parts of the tablecloth don't come apart.