I'm looking for some scree slopes for some research and was hoping for some recommendations.
Not inside a National Park or designated wilderness (not allowed to collect rocks from those locations).
Preferred locations: Bay area or Sierras from Sierra National Forest (North of Kings Canyon) to Tahoe Nat. Forest.
Within a few of miles of the road would be ideal, so it doesn't require an overnight trip to get to.

A scree slope close to a road not in a wilderness area or NP? Look no further than Dunderberg Peak in Inyo National Forest. Dunderberg Peak is a Mt. Everest of scree and close to the end of the Virginia Lakes Road off of Conway Summit (Highway 395 south of Bridgeport). I've made close to 400 ascents in the Sierra's, Dunderberg Peak is the only climb I wish I'd never made - the scree is that bad (or good in your case)

I second that. It's the mother of all scree slopes. You can see the scree slope above Moat Lake here:

https://photos.app.goo.gl/rCj7JD5JCAj2rFcdA

or here (from Moat Lake):

https://photos.app.goo.gl/4KQcscZyGbMVwXm99