drdna:

I think there is a hybrid between Q. alba and Q. michauxii, called beadles oak. I don't think the acorns are unusually large, but the tree is supposed to be very fast growing and gets rather large.

--spruce

Quercus Macrocarpa is known to have big acorns. Look on Oikos tree crops web site, it may help you or not, but worth a gander.

I forgot to mention Mossy oak natives nursery also has hybrids of oaks.

Mossy oak in fact sells Beadle's Oak (michauxii/alba hybrid). Although it's from a Mississippi seed source, I think they say it's good at least to zone 5. Might be OK in z4b since even michauxii itself can grow in z5 & alba to z4 or even 3b.

As a side note, it might also have a chance at good fall color, rare in most hybrid oaks, since Q. alba usually does, and many individual specimens of michauxii also can be a nice red in fall.

I have some Q.macrocarpaXmichauxii grafts growing here, but still too young to produce acorns.
For sheer acorn size, it's hard to beat Q.macrocarpa from southern/western reaches of its range.
I have one selection, from AL, that has acorns that run in the 6-8/lb range - with caps removed. Biggest I've run across yet.

Lucky - those are HUGE. Got any acorns to send me?

Of course, you'd have to ship them in a piano crate...haha.

I have a Bur Oak in my front yard that I grew from one of those giant acorns collected in Auburn. That acorn was almost the size of an egg. It has been a fairly slow growing tree for me though, compared to Q.alba.

Bur oaks seem to be a very diverse species. Major variation in growth rate, mature size, acorn size, etc. Growth rate can range from slow to fast, and acorns from small to large. Mature size anything from barely bigger than a shrub to a mammoth beast.

Q. michauxii is hardy to at least zone 4b. The Dominion Arboretum in Ottawa Canada has a 50+ year old one which would have seen -25F many times, and all time lows of -33F. Even the AVERAGE January low temperature is 6F.

hair,
Don't currently have any of those AL acorns.
My grafted specimen of the AU-CVM #1 tree suddenly wilted and died down to the root collar several years back, and I had to re-start it. Current incarnations of it are not yet big enough to fruit here.

Have some TX & OK seedlings growing here; acorns mature later than those from more northerly provenances, and the trees are often still sporting full green leaves when freezes hit, but I've not had any issues with winter die-back.

On my site, bur oak has been one of the fastest-growing of the oak species; easily outpacing any of the red/black group, and only challenged by some of the Schuettes and Bebbs hybrids.

Lucky, this past growing season was at best mediocre, but 'Kreider' burr oak has an at-least 36" sprout on the top -- near 25' after 9 seasons (& grew little the first couple yrs). It has nearly caught up w/nearby Shumard oak. Also surprising that it's still maintaining a distinct central leader.