If, as Sue asked, you do indeed have the Desktop CC version of Photoshop installed, you can do this:
Open the Libraries panel in Photoshop, right-click on the pattern you're interested in, and choose "Create Pattern Preset" from the pop-up menu. Now look in Edit > Presets > Preset Manager and choose Patterns for Preset Type. Find the desired pattern, and hover the mouse over it. You will see the dimensions in pixels of one tile. NOTE: you must have Show Tool Tips checked in the prefs to see this.
Make a note of these dimensions, and click Done. make a new doc with these dimensions, and Edit > Fill, Contents = Pattern, choose your pattern, and click OK. You will now have a doc with a single tile in it.
I find that most of my patterns created with Capture are one of only a few different sizes, depending on if the patterns are rectangular or hexagonal, so you can set up some New Document presets for these sizes.