Removing any "plant material" removes the organic matter the soil needs and that will feed any earthworms you do have. How much orgainc matter is in the soil now? 6 to 8 percent OM is what your goal should be.
Tilling the soil can bring other "weed" seeds to the surface where they can germinate and grow. People often will till soil a couple of times a week or two apart to disrupt the growth patterns of these "weeds".
I would work the Alfalfa pellets into the soil before seeding rather than while or after seeding. The grass seed you do spread should be slightly covered with soil after spreading.
The seed bed will need to be kept moist until those seeds germinate and are up and growing quite well.
Why did you spread that limestone 2 years ago? What type of limestone was spread? What is your soils pH today? Did that limestone do what is was supposed to do?

Thanks, Kimmsr.
So do you think I should just till and leave all the weeds in it? I do leave the clippings on the lawn when I mow, so there is some OM in the soil from that. I suppose I have to send some soil in for a test.

I am in an area that has very acidic clay-ey soils with poor drainage. When I overseeded my front lawn two years ago, I applied powdered limestone - the cheap kind in a bag from Lowe's - at a rate that someone told me (don't remember how much). I had some left over, so I spread it in the back yard in anticipation of rejuvenating the lawn there some day.

Most turf grasses grow best in soils with a soil pH between 6.0 and 7.0 and adding enough lime is the fastest way to get that pH up there if it is needed. A bag or two seldom will do anything, especially if you need 3 pounds per square foot. Start with a good, reliable soil test from your North Carolina State University Cooperative Extension Service which can guide you in how much limestone you might need.
Perhaps these simple soil tests will be of some help, also.
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

Here is a link that might be useful: NCSU on liming

Kimmsr,

Thank you so much for taking the time to help me with my lawn! The file you linked me to is also very informative. I will try to get the soil test in before the weekend and go from there.

Thanks again.
Kat