The floor in my basement is dirt. Can the walls still be insulated and if so, how?

Are the walls framed or are they concrete/stone?

We could help if you come back and answer mtconc's questions

The walls are cinder block. I live in TN and the property is not level. At the entrance to the basement, the walls are 7 feet and go down to 2 feet at the front. Would spray foam on the basement ceiling work?

The walls are cinder block. I live in TN and the property is not level. At the entrance to the basement, the walls are 7 feet and go down to 2 feet at the front. Would spray foam on the basement ceiling work?

Spray foam would work but is expensive. You asked about insulating the walls and now are talking ceiling. I'd skip the walls and just insulate the bays between the floor joists with a vapor barrier and thickest batts you can get in the bays

I agree w/bob.. spray foam works good but is expensive..
Go with the insulation in the bays
Are you going to finish that area or is is just storage?