I STINK at identifying trees! :-(

I STINK at identifying trees! :-(

I've been looking for a good tree identification key.. I have access to a nice Symonds book that I've been eyeing and the Dirr Manual of Woody Plants is also on my 'wish' list.. but i'm looking for something that I can just throw in my backpack, a more high level 'idiot' guide or identification key, specifically for trees in the NE US. (A guide that may have a hackberry for example) Any suggestions? this is the kind of problem I'm having.. I found something that I THINK is a dogwood, but it has leaves with serrated edges. I'm stumped. I know there are 100+ types of dogwoords, but do they have these sorts of leaves???? These are the types of questions I'm facing, kind of 'newbie' ish. I was trying to identify based on flowers but then I saw the leaves... ARGH! Please be kind.. I have not a clue. :( The tree I THINK is a dogwood but with the serrated leaves the full tree and here's one that I THINK is a prunus of some sort.. they're in a very landscaped area, so there's a good chance they arent' native to my area (CT). I feel so clueless. thanks for your infinate patience.
Some flowers growing in our backyard

Some flowers growing in our backyard

Pics from my place

Pics from my place

IDs please and thank you

IDs please and thank you

Replacement suggestions and apple tree care

Replacement suggestions and apple tree care

Amaryllis and starting seeds indoors

Amaryllis and starting seeds indoors

My Container Garden picture…

My Container Garden picture…