In a large stock pot, add sliced yellow squash, zucchini and onion. Sprinkle 1/2 cup canning salt over all, cover with cold water and let sit 2 hours. Drain, but do not rinse and set aside.

In a large saucepan, add sugar, vinegar and spices. Bring to a boil over medium high to high heat, stirring often. Remove pan from heat and pour mixture over drained squash. Let sit 30 minutes, stirring once in awhile to thoroughly blend.

Using a slotted spoon, fill prepared jars (wide mouth pint jars work best), pushing vegetables down in jars. Ladle hot liquid over vegetables leaving 1/4-inch head-space. Use a plastic knife and move up and down around sides of jars to remove air bubbles; top with more liquid if necessary,

Cover jars with lids and rings and process in boiling water bath 10 minutes. Remove jars from water bath and let sit on a kitchen towel on your counter-top 24 hours undisturbed. Jars are sealed when button in middle of lid is depressed and can't be moved.

Store in pantry up to 1 year. Opened jars must be refrigerated.

Cooks note - recipe is easily divided or doubled. Vinegar and Sugar ratio is 1:1 so adjust accordingly along with spices (less spice when divided, more spice when doubled).