Weedlings

[Treeflea24]

Ive been finding these weeds everywhere around my garden (NW Ohio). I thought maybe these were from seeds that somehow arrived in the mulch that I put down last year, until these started springing up in my gravel beds also.
When I look at the leaves, my limited knowledge and bias towards trees makes me think these may be tiny fruit trees, pear or apple, maybe? The serrated leaves and the shape is what sends me there. When I pull them, many still have the seed attached, and the size of it reminds me of an apple seed size... The stems have a reddish tint.
They seem to be distributed about everywhere (not just in the garden), and with the size of the seed I doubt they are wind blown - my hunch is they came in a birds GI tract.

There are a few crabapples around my property, and there is one Callery pear tree that is several hundred feet away from where Im finding these. Ive been reading about that tree and how invasive it can be and thats another thing thats got me wondering what these are. The other hunch is dogwood, there are a lot of those around me also, and these weedlings look like they might have opposite leaves. I tried to show the leaf veins too, I think they might say 'dogwood', but the serrations dont seem to agree. Maybe its just some weed with a big seed.

Pics below. Let me know your thoughts.

[beenthere]

Leaves look like a nettle. 

[WDH]

My first thought is some type of cherry. 

[SwampDonkey]

Cherry, any wild cherries near by? Could be black, pin or choke. Black and pin cherry grow like weeds here in the back yard. :D

[Treeflea24]

Yes, there are several black cherries nearby. I think yall have solved it, Thanks!
I've been growing oak and walnut seedlings in this garden and transplanting them in the fall for the past 2-3 years. Now I will be able to add cherry to my crop.