Check out this photo, submitted to MUFON (along with a full description, which you can read below), featuring a contrail of a craft flying in circles. The witness submitted multiple photos - just like this - and claims to have seen the object flying around, but I can't quite see it:
I was heading towards my gym, heading southward when I looked up in the sky and noticed an object forming contrails (puffs of smoke) while the object was traveling in counter close-wise circles. I stopped to take pictures and then I proceeded to drive towards the gym while observing the object. I took a few more pictures once I parked then I notices I can see the object was still in the circle making puffs of smoke as it was circling counterclockwise. While outside I couldn't see the object directly or hear any engines or motors.
This could simply have been a jet, but that doesn't really seem to jive with the witness' report. Have you seen any strange contrails or crafts in Pflugerville recently? Report your sighting.