How to find your existing pattern
The Patterns can be found in a top-level menu near the Posts
menu item.
From the Patterns menu, you will be able to see all of your recent patterns, whether they are synced or unsynced, and if they are active or not.
Upon activation, you'll notice the Patterns menu is now under the Posts menu item in the admin. Beneath that are pattern categories, and the settings for this plugin.
Patterns are a slightly hidden post type by default (they are stashed under Appearance in classic themes). Pattern categories are totally hidden and only exposed if you know the direct URL.
A top-level item was chosen so that the categories and settings could live right next to the patterns.
For those who choose to hide all patterns, you can still hide the Pattern Wrangler settings under Appearance, which is where the original Patterns menu item lived prior to plugin activation.
In Block themes, the Patterns menu item is completely hidden but linked to in the Full-site Editor. Like pattern categories, these are totally hidden unless you know the direct URL.