If it takes 15 minutes to find each worm, then he catches 60/15 = <<60/15=4>>4 worms per hour.
In 6 hours, Kevin catches 4 * 6 = <<4*6=24>>24 worms.
If he feeds each toad 3 worms, then he has 24/3 = <<24/3=8>>8 toads in his shoebox.
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