My Favorite FREE Great Sewing Notions  
 

• Soap Slivers - I always keep them for the best, washable markers around!  I keep them stored in an old prescription bottle..
• Fabric Tubes - best pressing 'seam roll' around...especially for pant legs.  I'll never forget, though, that when I was doing custom dressmaking and my son was about 6 or so - I didn't notice he had drawn all over the tube with red crayon....UNTIL I turned the silk plaid pant leg right side out and saw the embedded red crayon on the pant leg for a customer!  Loved that drycleaner's magic!  Sew.... hide yours.  I'm sure you can have one free for the asking at any fabric store. 
• Painter's Tape or Post Notes   - quick and EZ for sticking on the bed of your machine as a seam guide.  I grab my roll of brown half-sticky painters' tape frequently during classes with my young girls.  A Rubber Band can also be slid over the bed of a free arm machine and easily moved.  Be a "Guide Watcher", not a "Needle Watcher" for straight seaming!