This speech bubble and the next are both really cute, the borders are blue with jiggly patterns that could express talking about something excitedly.
This pink heart shaped thought bubble is perfect for thoughts of love and romance. Cute and romantic, might be a nice way to pin a note on a picture of you to send to your sweetie on Valentines or an anniversary.
A simple cartoon style callout that looks like it's been drawn in charcoal. The main background is transparent, so it works well on any photo or well... anything you want!
A large, rectangular cartoon callout with slightly rounded edges. The outline also looks drawn in pencil but is much cleaner, less cartoon grungy than some of the others so it would work for a bunch of different pictures.
Have your head in the clouds? This bubbly, fluffy thought bubble is one of my personal favorites and reminds me of time spent happily daydreaming.
With the icicles dripping from this one it could either represent being cold (perhaps on a picture of someone during winter) or even an icy cold comment said in anger.