You can share the Notes created under your Gmail account by adding the Gmail account that you're using on your iPhone to your Mac. To do this, go to Settings → Mail, Contacts & Calendars. Select the Gmail button and add your account information and be sure to check the box next to Notes. If you already have your Gmail account set up on your Mac, follow the same instructions but when you access the Mail, Contacts & Calendars area click on the Gmail acct on the left and a list of options will show on the left. From there you can see if the Notes option is selected. If not, check the box and they should sync. One caveat: some CalDAV notes show up in Mail app instead of the OSX Notes app. I'm not sure about Gmail.
If none of the above work, I recommend checking Help online in Gmail (or similar; that's how I solved a shared calendar sync problem.