This one in Portuguese - my translation left something to be desired, but the pictures are fairly self explanatory. Direct link to pictorial ~ crochet petal edging. Beautiful, but wouldn't want to have to cover a vast area with this stitch.
Crochet - Granny Spike Stitch - leaves fewer gaps, because the second double crochet is crochet through the top of the second double crochet of the row below. Possibly use a dc,tc, dc pattern in the clusters? From Do It Darling.