Which Grass Seed is Best for Complete Shade?

Hello, this is my first time posting on this forum!  Thank you for providing such helpful and informative articles!

My mom and I have a small yard with five large Ash trees, sandy soil with a very high water table (water collects under our house most of the time and we have to pump it out); moss grows in our front yard.  We live in zone 5a. 

There are two or three places that receive a tiny bit of dappled sun for a couple of hours, but mostly our yard is completely shaded; in fact, the only thing that grows there are dandelions and a few other weeds, no grass.  I'm going to till the entire yard this Fall and sow from scratch because our ground is so uneven.

I know that you suggest Tall Fescue and said that it "tolerates" shade, but I had to ask if it would be able to thrive in such a shady environment?  Our local garden center has a blend called "Shady Place Mixture" and I wondered if that mightn't be better.  It has Chewings Fescue (Shadow II), Creeping Red Fescue, Hard Fescue, Bluegrass and Ryegrass.  Also, in our area they have a "Native Wonder Mix" with Buffalo Grass (Bowie) and Blue Grama.

Which way do you thing think we should go?

Thank you for your help!

My impression is that tall fescue is more shade tolerant than any of the grass varieties mentioned in the seed mix you mention.  I would stick to tall fescue.

At least half my yard is shaded by large pecan trees and fescue is all that we can grow there. Some of it even survives the dogs!