The shelves in the left cabinet hold a bin containing trim, a box of lace, and a box of patterns. The boxes are the type that hold reams of paper (nice and sturdy!) covered with self-adhesive paper to make them prettier.
This size box works well for patterns.
(Though I keep frequently used patterns clipped to a hanger in the closet so that I don't have to iron the pattern pieces flat every time I want to use them.)
The upper shelves hold my sewing tote along with boxes of ribbon, trim, notions, etc.
The shelves in the right cabinet hold my fabric stash (which is currently quite small!). I always pre-wash my cottons before adding them to the stash so that I can pull them out and use them whenever the mood strikes. Every piece of fabric has a label pinned to it so that I can tell at a glance how many yards I have without having to unfold the fabric.
A set of Antonius sliding baskets hold my scrap stash (which is currently quite large!). Pieces of fabric smaller than one yard are rolled up and rubber banded. This keeps the scraps tidy and allows me to easily find what I'm looking for.
I need to get creative and find ways to use all those scraps! :)