Looks more like an Ash seedling to me, but what do I know!

How many thousand would anyone like? I have just filled a 2 gallon bucket with newly germinated seedlings, for the third time in the last week.
Odd things, when just germinated they come out easily, at 6 inches tall they are fiendishly difficult, at 3 feet the are dead easy again.
If you snap them off they re-grow with multiple stems.

I know your problem, Owd. I had the same one with the ash tree next door growing right near the fence. It took a bit of doing but I managed to get them to chop it down. I used the argument about height equals length of root;, drains and foundations. Took a while but I finally got there.
I felt like screaming when I had to pull out what seemed like thousands of the darn things.

That was two years ago but I'm still pulling out seedlings though only a few now and then.