FreeBMD has a marriage entry - although John's page number has been mis-transcribed (I have reported it) as 659, where it should read 859. And Mary is Mary Alice.
December quarter 1909 - Anglesey, 11b, page 859
This is not the marriage you are searching for. It refers to - Mary Alice Jones (age 28, of Twrgwyn, Amlwch dau of Jenkyn Jones, seaman) who married Thomas Owens (29, seaman of Hoyhead, son of Thomas Owens, seaman) on 15 Dec 1909 at Amwch Church. (On FreeBMD Thomas's entry has been transcribed December quarter 1909 - Anglesey, 11b, page 8__).
A different possible marriage for John Jones & Mary Jones on FreeBMD is December quarter 1909 - Carnarvon 11b 744. NorthWales BMD shows that this was a civil marriage at Caernarfon (ref CAE/54/E195).