Magnet pictures an advertisement from the mid 1950s promoting Blue Bonnet margarine, the only one that "looks like, cooks like and tastes like the 'high price' spread!"
Surprisingly, though the first margarine patent was issued in 1898, the buttery-looking, quarter-pound stick promoted in this advertisement was not introduced until 1950 when president Truman listened to consumers, said fooey to powerful dairy lobbyists and signed the Margarine Act that gave margarine manufacturers greater freedom in marketing their products. Note that in this ad 6-7 years later, Blue Bonnet was nonetheless careful not to mention the B word. It took another 17 years for the last of the trade-restraining taxes on margarine to be repealed.
Standard Brands acquired the brand in 1943 and Blue Bonnet joined the ConAgra stable in 1998. I have read that Standard purchased the brand from a small independent company but so far haven't learned the company name but it dates to at least 1897 and was founded in Texas where the lupinus texensis, aka "bluebonnet," is the state flower.