Not the best candidate for bknsai. If they survive your collection in mid summer ( being white oaks I'd say they wont) they grow slow. Like the slowest growing tree in Michigan. It will be many years to grow them out.
There are more trees not to waste your time growing in Michigan than there are to use as bonsai.
No birches.
No oaks.
No maples.
No red or white pine. Jack and scots are good.
No willows.
No junipers.
Trees to look for are
Elms
Hawthorns
Tamarack
White spruce
Jack pine
Scots pine
Hops hornbeam
American hornbeam
The pines are the hardent to collect and live.
The elms the easiest.
All should be collecTed in the spring for best success of surviving.
Some may disagree but they don't have temperatures like we or at least I see in winter. Not enough time here for roots to heal after a fall collection.
I don't know where you live in Michigan but there are a few bonsai clubs.
Next weekend the Four Seasons Bonsai Club is having its annual show at Bordines Nursery in Rochester Hills. I make the trek down there every year. If you are near come see us.