The big push between the Creationists and the Evolutionists is of more recent vintage.
Seriously, I suspect Lamarckianism has been dropped from the biology texts by the publishers simply to avoid risk of loss of sales as state laws on the matter are "reinterpreted".
We have some Freepers with experience in the textbook business. They might know. I just did a quick google.com search and didn't find anything one way or the other although it has popped up in some of the discussions concerning banning of either Creation stories or Evolution (both having been banned at different times by different folks for various reasons).
Basically you have had your ass handed to you, and you are acting like the frat boys in "Animal House."
"Thank you sir, may I have another?"
I don't have a more recent high school text at home, but I'll be back.
Here's some perspective on Lamarck in textbooks. This essay is a decade old, but still being referenced.
http://www.textbookleague.org/54marck.htm