1. Before doing anything get a good, reliable soil test to see what that soils pH is and what the levels of Phosphorus, Potash, Calcium, and Magnesium are. Then dig in with these simple soil tests,

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.
to see what else about that soil needs help.

Possibly, once you know more about the soil and can make knowledgeable decisions about what to do about the soil to make that into a good and healthy soil, then you can decide if tilling, which can help with leveling, or total removal of the present sod (often not necessary) and replacesment with some kind of soil and then laying sod or seeding, or whatever.

I'm trying to kill my sod to start a meadow. You're already there! I don't see anything to recover.

You're in a perfect starting position to re-assess whether you want that much lawn, or want to do something else with it.

Oh, and redwoods work best with no grass under them. When was the last time you went to a redwood forest and saw lots of grass? Never.

Kimmsr --> looks like our county extension here in California will not do a soil test. I am looking for options. Do you think one sample is enough or I should send samples from different parts of he garden? I wil do the drainage hole and the mason jar test.

Watch nerd: I do not have grass directly under the redwoods. But the shadow from the redwood falls on the lawn.

What city are you in?

The local California Native Plant Society chapters have pretty extensive information about dominant soil types.