I've noticed that I get a lot of traffic to my blog looking to learn how to make t-shirt flowers.
For my flowers (like below), I used this tutorial, but with t-shirt fabric. Also, I cut my pieces in more of a heart shape when folded, so when they are opened, they look like flowers with petals, instead of circles. I also DO sew them together, along with using glue, for extra strength. Does that make sense?;)
Here are a few more t-shirt tutorials that look like fun: