There is a small building on Ann Arbor and about 38th in Warr Acres that has a sign that says it is the location of the headwaters of the Deep Fork River. Where does the river actually emerge from the ground where one can see it?

Bigray in Ok

In a concrete culvert...

The Deep Fork River may be seen underneath the Centennial Expressway just south of I-44. It flows northeast and, eventually, southeast into Lake Eufaula.

http://geology.com/lakes-rivers-water/oklahoma.shtml

It crosses underneath Ann Arbor and actually runs under the Willow Walk apartments and crosses 36th street, meandering through Windsor Hills, crossing Meridian around 30th St, and on east through Will Rogers Park, & beyond, to Lake Arcadia, and yes, ultimately lake Eufaula, Picking up tributaries as it goes.

That sign on Ann Arbor says it's the headwaters starting point for Lake Eufaula, IIRC.

It crosses underneath Ann Arbor and actually runs under the Willow Walk apartments and crosses 36th street, meandering through Windsor Hills, crossing Meridian around 30th St, and on east through Will Rogers Park, & beyond, to Lake Arcadia, and yes, ultimately lake Eufaula, Picking up tributaries as it goes.

Is it one and the same as the creek that goes through Wills Rodgers Park?

^^Yes, that's it. It picks up a few tributaries between Ann Arbor and Will Rogers, but that's the one.

I remember when I lived over by 32nd & Ann Arbor, and much of it was being concreted in and we used to ride our bikes all around in there and go "creek walling" and see how far we could go. We would spend hours exploring through there, It was cool that we really didn't know where we were until we found a spot to come out and see where we wound up. There's a feeder that comes from the west and runs underneath Meridian around 26th street and then runs under some apartments or offices, and comes back out into to open a little further to the east. That was spooky riding our bikes through there. We had to have flashlights.