I don't know what I'll add in here, but I'll try my best to make you entertained. You are 15 years old. Until a few months ago, you thought you are quirckless. No sings appeared, until... You gained mental strength. Apparently, your quirk relies on your mental state. How strong you are. How strong your will is. At first, when you imagined things, they were so vivid, almost real even. Seeing that you didn't have to stick to the life of a normal person. There were a few months until the entrance exam at the UA Academy in which you always longed to come. Your quick is called "Imagination". Mainly, at a range of 2-3 meters, you can inflict a stun effect on your enemies. You can control their minds by making them travel into the place you imagined. Later on, little before the entrance exam you materialised your first object. It didn't last long until it disappeared, given the fact that that wasn't the main strength of your Quirk.