If you rename a flower and place it into a flower pot and then break the flower pot, the flower will revert back to normal name.

Example:

1) Rename a poppy (or other flower) to Minecraft.

2) Place the renamed poppy (Minecraft) into a flower pot.
3) Break the flower pot and the renamed poppy (Minecraft) will change its name from Minecraft back to poppy.

Update: This effect also happens when you place the renamed flower onto a grass block and then pick the flower back up.

Update 2: I can successfully replicate this effect 100% of the time.