How can I make a gallery of "boxes" of content consisting of an image and some text?
Module Image Field Caption

The Image Field Caption module adds an extra text area for captions on image fields. Similar to the alt and title text fields available with an image field, the caption text area can be used to enter text or html descriptions of an image.

The Readme.txt of this module details how you can tune/customize the image caption display, e.g. via theme templates (.tpl files), or via CSS.

Module Textimage

The Textimage module may be a good fit for what you're looking for. Excerpt from itsproject page:


  ... adds text to image functionality using GD2 and Freetype, enabling users to create crisp images on the fly for use as theme objects, headings or limitless other possibilities.


The project page of this module also includes some links about HOWTO manuals.

Other modules to consider

If the above modules are not what you're looking for, then I suggest you consider these alternatives:


Drupal 7 - How to Create an Image Gallery in Drupal contains some great docu about this topic also.
Talking Drupal #083 is a great podcast about creating a Gallery, and includes a lot of recommended modules for it. Just to mention a few of them (mentioned on the linked page):


Gallery formatter



  ... provides a CCK formatter for image fields, which will turn any image field into a jQuery Gallery.



Views Slideshow



  ... can be used to create a slideshow of any content (not just images) that can appear in a View. Powered by jQuery, it is heavily customizable: you may choose slideshow settings for each View you create.



Flexslider



  ... integrates the Flex Slider library with Drupal and several contributed modules which allows you to build responsive, resizable slideshows. Meaning the slideshows automatically adapt to the size of the browser window or device.



Node Gallery



  ... allows you to create multimedia galleries where both the galleries and the gallery items are nodes (as opposed to gallery items being file fields, like Media Gallery).



Multiupload Filefield Widget



  The File module of Drupal 7 enables you to select only one file at a time which can be very time consuming in case of many files. This module uses the 'multiple' attribute of html5 to overcome this problem and presents a widget called 'Multiple' that can be used with fields of type File.
  
  Using this Multiple widget in case of File fields it is possible to select more files at a time, which can be a big time saver. 



Multiupload Imagefield Widget



  As an extension to Multiupload Filefield Widget this module presents the same widget to Image fields. 



Field Focus



  If you are using ImageField and ImageCache, you might have had hard times trying to get Scale And Crop to show what you actually want of your images.
  That is what ImageField Focus was made for.
  
  It allows you to tell ImageCache what portion of the image you want to focus to, and what portion you want to be cut out.



Plupload integration



  Provides integration between for the Plupload widget to upload multiple files and Drupal. Plupload is a GPL licensed multiple file uploading tool that can present widgets in Flash, Gears, HTML 5, Silverlight, BrowserPlus, and HTML4 depending on the capabilities of the client computer.