Not Arlington, but if that big of a deal to you...Walmart in Hudson Oaks. Granbury Marina.
I go through gas fast enough in the mower for it not to matter...Mid grade or premium with Stabil. Run the mower out when storing, any gas left in the can after a couple of weeks gets dumped in the truck.
I fill up a couple of 5gal cans anytime I'm near Weatherford, Granbury, or a Buccee's for on-hand/generator/4 wheelers.