The SpeakOut! WordPress petition plugin includes the following features (and more) – the free version should be enough to create a single working petition.

Multiple petitions on one page (only 1 petition in free version)
Widget available
Easily added via shortcode
Set a goal for signatures
Single or multiple (comma separated) recipients of petition
Privacy – show only 1st character of surname (admin option)
Sender addresses are retained for follow up
Confirm email addresses (admin option)
Collect addresses or not (admin option)
Extendable via webhooks
Export data to CSV
Send emails or just collect signatures (admin option)
Verify signer’s email (admin option)
Message can be formatted using markdown syntax
Message sent with petition can be hidden from petition so that you can add your own text on the page outside the petition instead
BCC petition to signer (admin option and signer selectable)
Signers can choose to be publicly anonymous (admin option) (free :: Pro)
shortcodes [signaturecount] and [signaturegoal] plus other shortcodes for additional flexibility promoting petition
Multiple translations

Pro-only features

Multiple petitions
Message sent with the petition can be edited by the sender (admin option)
Nine custom fields including 1 drop-down and 4 checkboxes
Can be displayed in a page or as a widget
SpeakOut! can automatically increase your goal when you hit a nominated %
Message to target can be edited by the user
Integrates with Mailchimp, Mailerlite and Active Campaign
Support for andedot.com fund raising form
Enable hCaptcha or Google recaptcha to prevent bots
Display signers as table or as single line list (admin option)
After successfully signed, optionally redirect to another URL
Use plugin CSS or own CSS

There are plenty more features and options – suggestions are welcome.