To answer my own question, it is a Cornus Kousa, Japanese Dogwood. A little google search does wonders. I have certainly seen these in nurseries but maybe not when they were in bloom. It is amazing how a single tree can just stop you in your tracks and elicit the wow effect. A neighbor has a Cornus Florida I believe and it just stopped blooming. Also a beautiful tree, both in habit and in bloom.

With that many vines on the tree, not sure that the trees were mainly dead already, most vines are not trees best friends. As far as the deck being wooden and grill on it, if it's a gas grill should be legal as long as its not multi-family dwelling. In most cases, if done properly a deck built around a tree won't harm it. I know it's your property and I sympathize with you as you should have given permission, but the deck looks nice. In addition make sure it wasn't the vines covering the trees that killed the trees, because from the before and after photos, I do not see too much tree, just vines, wouldn't want you to get counter sued.

Try for an arborist - look for one that is certified. Also, try your local county extension agent's office. S/he can either help you her/himself or tell you how to contact your state lab for tests. Clear photos, - and maybe samples, if at all possible - would help for either. Another thought is for you to look in Google Images for photos of lichen - it MAY be it's only that growing on the trunks.

Hey, anoushehnawaz, I'm one of the community gardeners there, and am quite familiar with those wisterias. Those vines were planted there when the garden was built over a decade ago. The purple one in the foreground was abused and neglected for many years, and seemed likely to expire until "someone" started to try and train it to grow up and around the post. This is the first year it has bloomed to any significant extent. The white one is an awesomely rambunctious grower, and receives no care or pruning whatever, except where the branches droop down into the pathway it's planted next to. There's actually a purple-flowered variety mixed in with the white, but it's totally overwhelmed by the other.