Brennen Hankins shared this photo with KRTV on Monday afternoon.
Hankins serves in the U.S. Air Force and is assigned to the 341st Civil Engineering Squadron at Malmstrom Air Force Base.
He spent the last few days in Missoula attending MisCon (sci-fi/fantasy convention), and when he returned home on Monday, he noticed a sign placed in his yard.
He initially thought it was a political sign, but when he got closer, he realized it said, "Thank you for serving our country."
The person who left the sign didn't just leave a message, however.
The anonymous do-gooder also mowed Hankins' lawn and hauled away rose clippings.
Hankins said: Please pass along my thanks to whoever did this! (Pretty sure I have the generous culprit narrowed down to at least my block, but I'm not sure exactly who and nobody in my neighborhood is home to ask :-) )