They lie next to each other and swap sperm. Then the saddle (or clitellum) forms an egg capsule that they kind of shuffle down their bodies and deposit in the soil. Snails are more extravert hermaphrodites - they shoot each other with sharp darts, reel each other in (terribly S and M) and then impregnate each other using very, very long penises.
I managed to have a stomach ache and stay off school every time we had to the dissecting days loomed. eyes of sheep, poor little frogs and, yes, worms.
My late stepfather was a very enthusiastic nature lover, always remember the time mother and I were back earlier than expected from a shopping trip only to find him boiling up some strange smelling stuff on the Aga. Turns out it was a recipe he had found for moth bait!
Then of course there was the time that we found him and my Ds1 in the cupboard under the stairs with a jar of glow worms............
But even he couldn't answer the earthworm reproduction question. I seem to remember him phoning the Natural History Museum, but can't recall the outcome.
I'm doing it in stages. That's the bit I remember from school biology. The rest I've googled. However, it all sounds very complicated [but involved cocoons] and the baby worms emerge after somethingorother days fully formed [which sounds really cute]. I think I missed my true vocation as a biology teacher .