I have a 1923 'LARGE SIZE' Silver Certificate 1.00 bill.

-Register of Treasury signature is HV Spellman
-Treasurer signature is Frank White
-SN is = Z77885759B
-Blue Seal

Can someone tell me what it's estimate value?
Thank you!

What is it's overall condition? Crisp, like new? Worn? That'll effect it a lot. You can try to see what similar items (if you can find any listed) are selling for on e-bay or similar forum. You can also stop by a coin and currency shop and see what a similar item is selling for (again, if you can find any on display). Alternatively, you can ask the proprietor to give you a quote. Keep in mind that any quote they'd give you would be what they'd be willing to offer you for it, knowing that they would then turn around and sell it for a profit.