Combine first 5 ingredients in a large bowl.
Stir together squash and next 3 ingredients; add to cornmeal mixture, stirring until blended.
Pour oil to a depth of 1/2 inch into a deep cast-iron skillet; heat to 350°. Drop batter by tablespoonfuls, in batches, into oil; fry 3 minutes on each side or until golden brown. Drain on paper towels; sprinkle evenly with 1/2 teaspoon salt.
* 6 medium-size zucchini squash may be substituted for the yellow squash.