To create this widget you need to select a Custom widget (the last widget in the dropdown add widget menu)

Segment: Organic Traffic

Dimension: Month of the Year (for example)

Metric: goal Completions All

You can choose to track all goals completion. 

Or you can choose to track organic traffic for specific goals:

In step 2, you can edit the widget title, widget description, you can choose the format and size of your GA widget:

During the last step, you can choose to hide metric or metric's change:

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