How could I make an array of Rects in C Sharp?

Generally I prefer working with Lists rather then Array's.

So To Begin with ill would start by making a new Class with all the properties i need. This can be on the bottom of your script if you dont want bother with a whole new file.

 class InvetoryClass {
     public Texture texture;
     public string itemTitle; /// i am just guessing!-) 
     public float width;
     public float height;
     /// class constructor 
     public InvetoryClass (Texture _texture , string _itemTitle) {
         texture = _texture;
         itemTitle = _itemTitle;
         /// here you can also add addition code thats handles something upon creation
         /// for example if you wanted the width to be stored automaticly 
         width = texture.width;
         height = texture.height;
     }
 }
 

make sure you are using System.Collections.Generic;

now its quite easy to make a list thats is based on that class like this:

     // define the list
         List<InvetoryClass> InvetoryList = new List<InvetoryClass> ();
 
         // make a invetory Items
         InvetoryClass invetoryItem = new InvetoryClass (theTexture, "theTitle");
 
         InvetoryList.Add (invetoryItem);
         InvetoryList.Add (invetoryItem1);
         InvetoryList.Add (invetoryItem2);
         InvetoryList.Add (invetoryItem3);
         InvetoryList.Add (invetoryItem4);
         InvetoryList.Add (invetoryItem5);

access properties like this InvetoryList[2].itemName

Check thiswiki for the whole functionality's for List (Remove , count , etc).