Cluster or bobble
There are a variety of different methods for making 'bumps' in your pattern with crochet. A CLUSTER in the same space would suffice.
It depends on the size yarn/thread you are using. Try this:
*YO, insert hook in free loop of st 'indicated' (this would be a free stitch where you wanted to make your bump), YO an pull up a loop, YO and draw through 2 loops on hook; repeat from * (1 or 2) more times (depending on the size of the bump), YO and draw through all 4 loops on hook.
Hope this helps.
Knit 2, Purl 2, Knit 2, Purl 2, Knit 3......Darn!