Sept 5-7: Wisconsin Sheep & Wool Festival, Jefferson County Fair Park, Jefferson, WI

Sept 27-28: National Alpaca Farm Days, C&M Acres

Oct 2-7:  Fall Yarn School,  Harveyville Project, Harveyville, KS

Oct 9-12: Stitches East, Hartford, CT

Oct 18-19: New York Sheep and Wool Festival, Dutchess County Fairgrounds, Rhinebeck, NY

Oct 24-26: Heartland Fiber Retreat, Hotel Pattee in Perry, Iowa.

Oct 24-26: Vogue Knitting LIVE! Chicago, IL

Nov 1-2: KnitXMidwest, Walnut Woods, Des Moines, IA

Nov 16: Shepherd's Market Fiber and Fabric Festival, Amana Woolen Mill, Amana Ia.

Feb 19-22, 2015:  Stitches West, Santa Clara, CA

Another good site is:
Knitter's Review has a calendar of yarn related events world wide on their website