My Parents Are Holding My Property Hostage.

Hello, first time using this subreddit, hoping to get some help. I (21M) recently had a bad fight with my mother and step father, which has resulted in me no longer being welcome in that household. I told my mother in our last interaction that I would be over to pack my things and that I would never be returning. I have stable housing with my friends, but I still had many of my belongings in my old room, which I only vacated about 5 months before this. I arrived at the house today and neither parent was home, so I entered and grabbed about 80% on my belongings. When taking one of the last boxes outside to my truck, my mother and step-dad returned and immediately became confrontational. I attempted to enter the house again for the last several items, many of which are valuable car parts and sentimental items, but was barred from doing so. What are my options for getting these items into my hands? These items are absolutely my property, they are not gifts and my parents have to reason to hold them from me other than spite.

EDIT FOR CLARITY: I live in Boise, Idaho. Some comments asked for my location.