When you dream about pizza, it's possible you want to fulfil an ambition but it will require you to divide the responsibility and share it with others in order for it to come to fruition.
Another interpretation is that pizza is associated with good things so perhaps something has turned out the way you wanted it to lately and you feel generally positive about life.
If you were ordering pizza, perhaps you recognise the number of options you have- if you had trouble figuring out what to order- this may be a reflection of something you are struggling to decide upon in your waking life.
If the pizza arrived and was missing something- a topping or the cheese for instance, you might be feeling like you are missing something in your life right now or not getting everything out of life you want to.
If you were watching a pizza in the oven in a dream- perhaps you are keen to find out how something will turn out at present and watching it closely so you can have an idea of the end result.
Frozen pizza can signify your personal savings. If you are saving for something right now- it could be symbolic of that accruement of money. If you were eating the pizza- perhaps you are worried about delving into your savings and how much will be left.
Another interpretation is that if you were eating a microwave pizza- you are hurrying something along- perhaps at too fast a pace. You might need to consider slowing things down in order for it to fair better.
A pizza box can represent a message that is coming your way in the near future. If you are expecting news that might be why you saw the box in your dream. If you were delivering the pizza, however, you may feel the need to pass on a message to someone else or have little control over the information you convey in your waking life.
Finally, if the pizza was delivered to you at your home- maybe you want to have things easy- you may crave things you are not willing to put in the work for.
Source: The Complete A-Z Dictionary of reams by Ian Wallace