I am going to be making a "pocket of aces" cake soon and I will be using two sheet cakes (15" x 11") on top of each other. Where can I find a cake board big enough for this? TIA?

Hobby Lobby carries round and sheet cake boards in a multitude of sizes. I've purchased boards for 11x15 sheet cakes there.

I'd stack several boards for a cake that size and cover them (all together) in a fancy foil.

HTH

I like to use the 1/2" foam core boards and cut them to size. they're very sturdy.

I'm thinking I'm going to need a 20" by 20" board, since they will be slightly off center of each other (make sense?). Where do you get the foam boards, I've heard of them on here before and they have said Michael's, but what section of Michael's? Thanks again for all your help!

Any cake supplies store should have he cardboard. Foamcore is in the framing department.

At our Michael's the foam core is usually in the art section. It's usually on an end cap of an isle next to the wall.