The Welcome Buddy flag is pretty awesome. It was in one of the trunks. I've seen one or two of them for sale on eBay but otherwise haven't found very much information about them. I assume (but definitely want to confirm) that the flags were used to show support for returning troops.
My grandfather shipped home in April 1919 -- a year to the month after he got drafted -- and some of his friends preceded him back to the states. The letters tell of a very warm welcome for the troops. My grandpa was pretty worried about finding work once he got home and asked his siblings and apparently friends about prospects. One of his pals from the war wrote about how easy it was to find work, that returning soldiers were front of the line to get hired and for good money.
After the war ended but before he got home, my grandpa asked his brother to make sure to take care of his tools so he could use them to find work when he got back. Like my dad, my grandfather was a plumber and apparently had already been investing in tools of the trade before he got drafted. My dad told me that at the end of his career my grandfather referred to himself as a "white collar plumber" because he was in charge of plumbing in all the municipal buildings in the city of Cleveland and so predominantly worked behind a desk. I always thought "white collar plumber" was pretty hysterical.
To me, the flag represents all of those feelings at war's end. My grandfather's anxiety about finding a job, his friend's excitement about work prospects, and the uncertainty about and then pleasure at the welcome they received when they finally made it home. Whoever bought and hung this flag maybe was particularly enthusiastic -- I've seen online the blue "Welcome Buddy" as a banner, without the fringe or the red and white sections that make a flag. It's in really nice shape but in my inexpert opinion was surely hung. It would be cool to find a photo of this one hung somewhere, like in front of the old house, but I haven't uncovered one -- yet.