Manufacturer's stamp.
https://www.nwitimes.com/news/foreign-language/e-c-pallet-company-set-to-move-into-old-queen/article_0dca610b-7eab-5509-b33c-d7493397df0e.html
Sorry. that post was super unhelpful. Here is the relevant portions.
"…Sergio Maga, owner of Indiana Pallet Co. in East Chicago, said he expects to close a deal today to buy the old Queen Anne candy plant at 604 Hoffman St. and move his operations there…"