This one looks pretty good!

22" wide board?Where'd you find it?What was the length?

Finding good clear wood I find is harder due to loss of the small sawmill that use to be very common.

I grew up in a logging family and we also had a couple sawmill.

There are only a couple left but not much grade lumber coming out of them

Looks like a big knot in it to me. but it will give it a nice look

Nice plank for sure. I only see light colored sap wood and darker heart wood.

20" wide I think, looks nice

Poplar grows like that .

What for?

The wider it is the more likely it'll warp.

I'm pretty sure you already know that, but, it in mind for your application.

Example:
I just make a "coffee table" 24 x 48 x 2 1/2" with my chainsaw mill. It's simply supported by champagne bottles that fit through drilled holes in the corner so the warp doesn't impact the structure. It is rough cut with bark on the edges so a little warp only enhances the rustic look.

Are you going to build a Jonboat ?

Your ahead even on stretchers to rip and glue. Gets rid of the cupping and warping! I glue all my stretchers and have never had a problem.

doesn't look like it was very hard.

How thick is that? In the pic it looks about 4-6 inches. Maple, I think?

Nice wide plank for sure, good looking wood. I am a fan of breadboard ends on tables, they look great and their sole function is to keep the cupping from happening on table tops. I have a table with a thinner top for hallways or behind couches, it would have cupped or warped long ago without the breadboard ends, they also provide a more finished look IMHO.

I know you can't use breadboard ends on stretchers, but you also aren't using hard maple for them either! I have a trailer full of basswood ready to cut up for my rat stretchers, still on the log but need to take to a mill to cut them so I can mill and shape them. I have some 72 inch + logs up at my buddies farm for making bigger stretchers out of too. I think if you cut a thin kerf in the bottom of the stretcher and add a strip of metal about .050 that will keep the basswood from cupping over time. the thicker wider boards for coon and fox and coyotes you can drill a hole through them in several places for a small diameter round rod to help reduce/eliminate cupping.

Does it have the heart in it?

It probably was flat sawn which means it will probably warp, but that it one nice plank. How much was it?

What are you building with this soft maple board ?
Hardwood lumber grades are based on clear cuttings per board. So the best lumber is on the outer part of the log. So sawyers are trained to take a few slices of a face of the log, then turn the log and so on. Species like maples ,boards with clear sapwood are more valuable than boards with heartwood in them. Sapwood on oaks and cherry are thin, so it’s the heartwood they want, but the highest grade boards still come off the outer faces of the log.

Looks like yellow poplar. It's one of the best for wide clear lumber.
If it's not dried, you should seal the ends.
The purple and green streaks are common in poplar. I have about a dozen boards squirreled away that are solid purple/black.
It's also a fairly stable wood, but as said above, to keep it flat the end should probably bread boarded or you could cleat the side that you won't see.

I'd use it for a project that allows you to keep it as wide as possible.