Okay, there are a bunch of guys from Texas in one of my online baseball leagues, so I asked them "what the hell is up with mums." Well, here are some of the responses.
"My wife said she used to make them on the side to sell to friends and others at school. Moved here in '98 9 years removed from H.S. So I'm not familiar with their traditions.
I know we didn't have these gaudy things in AZ."
"WTF is this shit?" (from a non-Texan)
"Well we take high school football kind of serious down here. One game out of the year (usually against a horrible opponent) is designated as homecoming. There is a dance and such but to the football game the ladies wear these mums. They were just a flower with a couple of ribbons when i was in high school but apparently they have grown to these monstrosities."
"I didn't realize other states didn't do it." (see, if you do it in Texas, you have to do it everywhere)
"I told you we take football seriously."
"Yeah but those things have nothing to do with football. They are just scary." (response to above)
And because I think 1/2 the league is OCD (OCD FTW!), they did their homework.
An entire article on the phenomenon From a wikipedia article on homecoming:
"At many high schools, especially in the southern United States, homecoming dates exchange "mums" on Homecoming Friday, to wear to the game and the dance. These are very elaborate corsages (for the girls) or garters (for the boys, worn on the arm) that consist of a large flower (usually a chrysanthemum) surrounded by a ribbon ruffle. Long ribbons, decorations and trinkets are hung from the mum which indicate the students' date of birth, name, class, interests, and messages towards other people."
Texas scares me more now than ever.