Hi Nelumbo.

What kind of spot do you have for the trees? Wet, dry, rocky, sunny or shade?

I love bald cypress, Taxodium distichtum (on my cell so I may make spelling errors). It is a conifer which drops its needles in the winter. Also if you plant it near water it might grow these absolutely awsome 'knees'. You can get a picture off google by searching cypress knees.

What else..... Metasequoia is similar but really a Chinese tree.

Nyssa sylvatica. Great fall color. Even has a version for swamps also, Nyssa aquatica. Why am I stuck on swamp trees this morning....

Bur oak or White oak are both majestic. Querces something are the latin names..... I will look it up if you can not find them. Bur oak has huge leaves and acorns. White oak has better fall color.

For a smaller flowering tree I love Cornus florida. Dogwoods have a bunch or cultivars but even if I just order a bunch of generic ones they reliably have excellent white flowers, red berries and extrodinary red fall color.

Tell us more about your yard.

Hi Toronado!

My yard or garden is in Estonia, and I have about 10 hectars free place ;). We have so many different spots - we have a little lake, and around it there is quite wet. There grows Chamaecyparis pisifera very well.. In Estonia we don't have rocks, so here are flat and fertile (maybe sandy). I also have Metasequoia, and it is one of my favourite tree. Taxodium distichum I like, too. You can see my blog, where everybody can see (in Estonian of course, some posts are in English), what do I do - www.tammelill.blogspot.com
I love latin names, too. Always, when somebody asks me to define some trees...
Some months ago I was wondering to have Nyssa. You are mind-reader! :)

Best wishes
Nelumbo

Some favorite American trees of mine that you could grow include:
Giant Sequoia (Sequoiadendron giganteum)
Tulip Poplar (Liriodendron tulipifera)
American Chestnut (Castanea dentata)
Southern Magnolia (Magnolia grandiflora)
Bald Cypress (Taxodium distichum)
White Oak (Quercus alba)
Red Buckeye (Aesculus pavia)
Yellow Buckeye (Aeseulus octandra)
Eastern Redbud (Cercis canadensis)
American Elm (Ulmus americana)

*If you decide to get a southern magnolia, make sure you get a cold weather cultivar like "Edith Bogue" or "Pocono".

Oaks:
Shumard Oak
Scarlet Oak
White Oak (mentioned)
Burr Oak (mentioned)
Red Oak Q. rubra
Pin Oak
many more

Maples:
Sugar Maple
Red Maple
Chalk Maple
Big-Toothed Maple
many others

MISC:
American Smoke Tree
Yellowwood Tree
Sycamore
Carolina Silverbell
Several Dogwoods Genus Cornus
Various Hickories (slow growing but very nice long lived)
Tulip Tree (mentioned)
American Hornbeam
Various Magnolia's
Thornless Honeylocust
Various Crabapples

MANY more.

Without knowing more about the site, climate and conditions, all anyone can do it rattle off a list of trees. Is that going to help you pick a tree that is suitable for your garden and adapted to your climate?

Climate is similar to US Pacific Northwest. I picked an inland site, since OP noted zone 5b-6a winter temps. Here is what I got.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Avg. Temperature
25 22 29 43 50 60 64 61 52 44 32 24
Avg. Max Temperature
29 28 36 52 59 69 73 71 60 49 36 28
Avg. Min Temperature
21 16 22 34 39 50 54 51 43 38 27 19
Avg. Rain Days
5 5 5 8 7 7 6 6 7 10 8 4
Avg. Snow Days
11 10 8 3 0 0 0 0 0 0 6 7

Looks not bad at all.

Here is a link that might be useful: Estonia Climate

How sure are we not introducing pest trees into Estonia???

dsieber,
Could happen, but it would be very difficult to predict that. In reality, only a very small percentage of introduced plants go on to be invasive. Of course some do, but which ones? BTW, same thing can happen from one region of a country to another, though that isn't as commonly known.

Arktrees

Arktrees

Thanks for the feedback you said:" Could happen, but it would be very difficult to predict that." I wonder if the Australians were thinking that we the released tons of rabbits or the introduction of kudzu to the South. I guess it says better be careful!!! If I was running a country I would not let anything in prior to running a controlled test in a test plot with controls to keep escapes away. Or Just do what the USDA does ban everything!!! I have 5 fantastic Bonsai Trees in the UK I had to put up for adoption due to USDA rule. Fortunately the Guy I adopted them has done a great Job. I visit them every couple of years.

dsieber, Ah we were talking about plants, not rabbits or animals. Also FYI, the biological control agents that are being looked at for various introduced pests are screened looking for side effect. But back to the rabbits for a moment, when those were introduced there was no though as to invasiveness of species, and a great many invasive as a whole were introduced before the concept even existed, let alone a population that cared. Don't know what you seem to be perturbed about, but it's not my issue. I was simply pointing out that only a small fraction end up invasive, nothing more, nothing less.

Arktrees