"Sometimes, when you make Crochet Circles, you want them flat, not ruffled or dome-shaped. Unfortunately, things don't always go your way..."
"Your crochet circle may not lay flat for various reasons. For one, you may be using more or fewer stitches than necessary for each round of the stitch. You may also be using the wrong hook size."
"Under each standard (UK or US), the description of crochet patterns has different terminologies. So, when following a pattern, you must interpret it according to the original standard."
"If the yarn you chose differs from the yarn the pattern recommends, your crochet circle may not lay flat."
"If your stitches are too tight, the crochet circle will form a dome. On the other hand, if your stitches are too loose, you may end up with ruffles."