Oopsie... my humble apologies...
You can get from Wawona TO Yosemite Valley and back.
But not the other way around. Go figure.
You'll want to look into the Hiker's shuttle to Tuolumne Meadows.
You should be able to get off at Crane Flat and then hike to the
Tuolumne Grove. The Mariposa Grove is much bigger but at least
you'll get to see a number of big trees.
Maybe they will even drop you off right at the Tuolumne Grove.
Although you may be "stuck" there all day (you should be able to
check out the Tuolumen Grove w/i a few hours)
Sorry about any misinformation...
I take public transit in the Bay Area but not in Yosemite.