I believe this pennant is from Oregon State’s 1965 Rose Bowl game versus Michigan. I’m assuming it’s from 1965 and not 1957, because we know what the 1957 pennant looks like from confirmed pictures during that game, and this one is much different.
I don’t want to guarantee this is from 1965, however, because the football player’s helmet doesn’t have a bar or mask on it. That would seem to date it closer to 1957 instead of 1965, but they may have just been using that picture to make it look like a “classic” football picture to make it look old school. On the other hand, the block style letters are more consistent with the 1960’s than the 50’s. If anyone knows for sure, let me know!