if u know of an area in your yard where it would be moist, even the lawn that's in a shaded area, to see if there's worms stick a garden fork all the way into ground and just wiggle it back and forth, make sure u are moving the ground and u will see the worms popping out onto the ground. Do it in the evening with a red color paper or plastic over flashlight as to not spook them.
I didn't believe it till I tried it.
It works.
Cabela's does have dew worms and trout worms in stock. 4.99 for 12 pk of dew worms,