jackb
Garden Master
One of the seed companies, and I don't even remember which one, included a package of free seeds with my order. The seeds were for a French Marigold called Sparky. I was not even going to bother to plant them, because I thought: how nice can they be if they give them away? I am glad I planted a few because they are rather nice. 
I once went to the Baker Creek store and bought 3 packs of seeds and they gave me 2 free ones. I felt kind of guilty because I didn't buy much. I passed them on to friends who had the right climate for watermelons.