Few, if any earthworms are native to N. America. They are not strictly necessary for a healthy soil.

If you do want to introduce earthworms... I know it might be a hassle, but you can identify different earthworms. If you get an id on the ones from Alabama, then you can simply find the same worm in Tn. Or, just turn under a few rocks around your area and get ones that have naturalized to the local environment. Top soil is removed all the time, and the worms come back. The best way to encourage their presence is to do what you've already described... supply their food (organic matter,) and they will show up sooner than you may expect.

Find a cow patty or five. turn them over, gently.

At a certain level of smell, you'll see tens of earthworms feasting. Transplant the patties to your beds.

Go into woods several days after a good rain. Dig up soil. Transplant to your yard.

You might consider trying a Worm Cafe(s) to see if this will work for
you. Providing a source of food for the worms will eventually draw them
to your soil. If you've never seen a worm in your soil, then adding a
few to your raised beds that will survive the winters should get you
going and you have had some good suggestions as to where to find a few
hardy worms to get started. However, they must have something to feed
on. Since it is so easy, I tried the idea of adding Worm Cafe's to my gardens and it's worked beautifully. My son made mine from cedar
but even a small plastic bucket with lid could be used to draw
in and provide food for the worms. Remove the bottom from the bucket and
drill big holes in the the lower portion of the bucket. Bury the
portion of bucket with holes into the soil and add your recyclables
such as veggie peelings, banana peels, spent coffee grounds and
filters, shredded cardboard, things that are ideal for compost piles,
into the worm cafe. As these items break down, the worms are drawn in
from surrounding soil to feed on the material. Of course, you want a
tight fitting cover to keep out flies and undesirables. Mine have worked
beautifully. There is no odor, no problem with unwanted pests and the
contents are digested and distributed throughout my garden soil as rich
worm castings. It will take a while to build up a good worm population
but it will work as long as a food source is provided for the worms. This is just
a take off on outdoor composting, of course, but for many urban
gardeners, maintaining an outdoor compost pile isn't feasible. This idea
provides a tidy, discrete method of composting in any garden setting. Best of luck with your new raised gardens
... Mary click for: Worm Cafe info