This bush is in a corner by a fence, it's about 3'-4' wide and about 6' tall. I'm not sure if the brighter green foliage is normal for it or if it needs a good feeding, but the leaves were all coming in more light green when it first starting leafing out. The white flowers are about an inch in size with 4 petals.

There's a lot of dead branches I'll be pruning out when it stops raining here (and a small tree growing in there too that'll come out), but I'm having no luck finding out what this bush is yet digging around online. It's near the Chicago area.

Edit: This time I Googled for any "white flowering bush" not limiting size or zone or flower type, and started looking through more images. Could this be a mock orange?

Reminds me of Mock Orange (Philadelphus species). Are the blooms fragrant? There are both fragrant and non-fragrant varieties.

Lewis' Mockorange (Philadelphus lewisii)
Sweet Mock Orange (Philadelphus coronarius)

It does look like mock orange, and the pale leaves are probably because it's the "gold" version, Philadelphus coronarius 'Aureus', in which case it is normal.

I haven't noticed any fragrance from the bush at all, but if it ever stops raining I'll go out and double check that. A neighbor has a lilac bush that is filling the air with its wonderful fragrance right now, so maybe I'm just not noticing the mock orange, the lilac is overpowering it, but I'll give it a good whiff close up tomorrow.

Unfortunately, there's no fragrance to it, I wish there was. If I really bury my nose inside a flower, I get a very slight hint of something like a carnation, but it's so slight that I could almost think it was my imagination too.

Thanks for the help IDing it.

Just an update that once I got my nose near the full bush pruning out the dead branches, it does have a scent to it. It's not a really strong overpowering scent like lilacs have, but even my neighbor made a comment how nice it smelled.

When it's done blooming, I'm going to really cut it back though, it has 6' long stems that look like dead wood and only the tips have foliage or flowers. It's so bad I really would love to cut it all to the ground (and it would then be easier to get rid of the maple and elm trees inside of it), but I'll do 1/3 each year like a sane person would.