I have to be honest and say I am flabbergasted at everyone here who has said she needs to check her bobbin tension.
If this picture is showing the bottom or back of her quilt as she says it does, SHE NEEDS TO CHECK HER TOP TENSION.
As a general rule:
Problems on TOP of the quilt are a result of the BOTTOM thread.
Problems on BOTTOM of the quilt are a result of the TOP thread.
If you do not believe me, google "Thread nesting on bottom of quilt" and you will get hits from several professional quilters and sites stating the above to be true, not to mention the numerous posts in previous threads on this very board about this exact problem.
For example:
Conversely, the reasons that thread can bunch up underneath your fabric have all to do with your needle tension.
1. Is the needle thread threaded correctly?
Cut the thread a few inches from the spool, and pull it through the needle. Re-thread, taking care to engage the upper thread completely in the tension discs. I always suggest to my students that they hold the thread on either side of the tension disc, and slide it back and forth a bit between the plates with a flossing motion. The tension discs need to “grasp” the thread snugly.
2. Is the presser foot up?
Duh. We’ve all done it!
3. Is your machine clean?
Frequent dusting underneath the throat plate and along the thread path will prevent all sorts of stitching and machine problems. Of course, good quality thread, a new, sharp sewing machine needle, and the correct bobbins for your make and model of sewing machine are basic requirements for producing good quality stitches. Frequent dusting, cleaning and oiling will also prevent these and many other stitching problems you might encounter