Try EC Brown in Thetford VT. I don't remember the route number but the nursery is on the west side (bottom) of Thetford Hill. You might call first to see if they have what you want.
Kathy

A great nursery that you pass by when you come down 89, almost to Sharon, is Dandelion Acres in Bethel. I was just there yesterday after not going for a few years and was once again very impressed with the high quality of the plants. I didn't look at the trees this time, but I could see they have a lot. Just get off at the Bethel exit (I believe its exit 3) then head toward Bethel for about a mile or maybe a little less. Or maybe they are the place that has only exotics?
Kathy

A great nursery that you pass by when you come down 89, almost to Sharon, is Dandelion Acres in Bethel. I was just there yesterday after not going for a few years and was once again very impressed with the high quality of the plants. I didn't look at the trees this time, but I could see they have a lot. Just get off at the Bethel exit (I believe its exit 3) then head toward Bethel for about a mile or maybe a little less. Or maybe they are one of the place you have tried?
Kathy

Once you've checked D Acres continue toward Sharon via Rt's 107 & 14 to Royalton Village there's one of those VT black & white directional signs to Stepping Stone Nursery across the White R. I don't recall whether they sell trees but are "in the loop" and can point you in the right direction.

I have purchased trees from the Arbor Day website. You have to join for a fee but you get free trees with your membership. They sell lots of small trees at a reasonable price. It's worth a look. Another place to look is Free trees and Plants. They charge $7.95 for two bare root trees.

You could contact the Vermont Association of Conservation Districts since you're looking for native trees. Conservation Districts often hold tree and other plant sales (although not in mid-summer) and they may be able to give you sources.

Claire

The New Hampshire state nursery sells wonderful seedlings of trees and shrubs, most of them are native. They are 1-2 year old seedlings and very healthy. You have to buy packs of 10 or more, but they are so cheap, $1-1.50 apiece. They only take orders throughout the winter and ship as soon as soil can be worked in the Spring. Hardy and well-adapted to our colder zones.

Incidentally, from what I understand some trees such as Hickorys and many Oaks are difficult to transplant beyond small seedlings because they grow a deep taproot, so you can only plant them as young seedlings. These would be ideal for starting from seed if you're so inclined.

Here is a link that might be useful: New Hampshire state forest nursery