Wood box, for mailing souvineers? ID ordnance?

[dan h]

I picked this box up at an auction. It appears to be a box used to mail things home in. I cannot tell if it was a box for ordnance items or not. There is a stamp on the inside lid that puzzles me. Can anyone ID?
It looks like a perfect box to mail a German helmet home in, but I tried it and it slightly too short, disappointed.
I thought it looked pretty cool and might be a nice display box to illustrate that purpose.
Is is German or American paint color?
Dan h

[dan h]

Inside stamping

Here is the ink stamp on the inside lid

[dan h]

Outside

Here is the ink stamp, that says entry permitted. It is stamped on the outside of the box in 2 places.

[fldjr]

Dan,
Cool lettering job on the box.
D.F.P.A. stands for Douglas Fir Plywood Association.
Regards,
Fred

[dan h]

Thanks for the answer, it must be a fairly common mark on US military wood boxes.