Sunshine Biscuit company introduced the creme-filled Hydrox cookie in 1908. (Oreos were not introduced until 1912.) The advertisement below is from 1951:
And this cute ad is from 1953:
This is half of their advertisement from 1958 (sorry I couldn't fit the whole thing on the scanner!) in celebration of their 50th anniversary:
They had been off the market since 2003. But Kellogg's - which now owns the brand -brought them back this year in honor of their 100th anniversary. So I snapped a picture of them when I saw them at the store, and here is how the package looks now:
I just enjoy comparing the packaging over the years.