Early Childhood Thematic Halloween Unit (Pre-K-K)
This site contains everything from bulletin board ideas to Halloween recipes and book lists. You can find activities that promote language development, gross and fine motor skills, and much more.
http://www.sbcss.k12.ca.us/sbcss/specialeducation
/ecthematic/halloween/

Pumpkin Potpourri (Pre-K-K)
This is a collection of integrated lessons involving pumpkins that were designed for lower elementary students.
http://www.teachers.net/lessons/posts/212.html

Pumpkin Unit (K-1)
This is a pumpkin unit created for a kindergarten class, but adaptable for other Grade Level. It includes a suggested trip to a pumpkin patch, pumpkin songs and finger plays and many ideas for integrating pumpkins into your language arts, math, and science activities.
http://www.education-world.com/a_lesson/lesson028.shtml

Estimating with Pumpkin Seeds (1-3)
This is an estimating activity with a printable worksheet in which students guess how many seeds are in a pumpkin and then work in teams to find out whose guess was closest.
http://www.lessonplanspage.com/MathEstimationPumpkin.htm