Rachel McAdams Engaged?

Do we have another secret Hollywood marriage on our hands? Rachel McAdams -- who once had a very public fairy-tale romance with The Notebook co-star Ryan Gosling, might be silently engaged to rumored beau Michael Sheen.

She was seen out and about in LA this weekend wearing what looked like a diamond engagement ring on her left hand. So either she wants us to think she's getting hitched, or she actually is heading down the aisle with Sheen.

The unexpected duo were linked late last summer and then had a make out sesh at the Toronto Film Festival in the fall. A month later, they were holding hands in McAdams' Canadian hometown, and that's about all the evidence material out there about these two.

Unless this bling becomes the best proof of all...