Don't throw that rind away. It makes delicious pickles.
I have loved this treat since I was a child. However, I almost wonder if I will be able to continue enjoying it.
Perhaps it is my imagination, but it seems like hybridization results in watermelons with thinner and thinner rinds every year. Every time I pickle watermelon rind, I feel like one of these years I am going to cut into a watermelon and find no rind there to pickle. I certainly wouldn't want that to happen.
The quantities that I list in this recipe are for just 1 quart of rind. Even a fairly small watermelon with thin rind will yield that much.
I believe that the spices that I use are fairly traditional, but you can find a lot of variety. For example, the Ball Complete Book of Home Preserving has a recipe with only cinnamon, and The Complete Book of Small-Batch Preserving has a recipe that uses lime instead of lemon.
Pickling watermelon rind is a two day process. On the first day, prepare the rind by removing the green part, and cutting the rind into chunks. Place the rind in a pickling crock, a plastic bowl, or a non-reactive pan. Cover it with a brine made from one quart water, and 1/4 cup pickling salt. Place a plate on top and weight it down to kep the rind submerged. Allow it to sit in a cool place over night.
On the second day, drain and rinse. Cover the rind with fresh water. Boil until it is soft, and drain again. Meanwhile make a syrup of 1 cup vinegar, 1 1/2 cups sugar, and 1/2 sliced lemon. heat and stir until sugar is dissolved. Add the rind to the syrup and cook until the rind is translucent.
For each pint, place 1 cinnamon stick (about 2 inches long), four cloves, and 3 allspice berries in the jar. Use a slotted spoon to add the rind. Cover with syrup leaving 1/2 inch headspace. Process pints in a water bath for 10 minutes. For quart jars, double the spices and process for 15 minutes.
High altitude instructions
1,001 - 3,000 feet : increase processing time by 5 minutes
3,001 - 6,000 feet : increase processing time by 10 minutes
6,001 - 8,000 feet : increase processing time by 15 minutes
8,001 - 10,000 feet : increase processing time by 20 minutes