What works better is attracting the native, deep burrowing earthworms to your veggie garden...one way to help is to have red wiggler, composting worms producing worm compost that can supply beneficial microbes to your veggie garden that attracts the deep burrowing worms. I can sell a deep burrowing earthworm (called the Alabama Jumper) that will do well in our clay soil, but I have manged to attract them naturally and think it is healthier to do that. They are expensive, and I would rather help people improve their soil to attract the worms.
I have a blog post about attracting deep burrowing earthworms: http://blog.txwormranch.com/2010/02/10/ ... arden.aspx
Good luck--mulched, living soil, full of microbes will bring a herd of deep burrowing earthworms to your garden "pasture".