Feel like I could post a million of these things, but a few older favorites that were out of print that recently surfaced on streaming that fall more into the "well-known artists later albums/side projects" category rather than total unknowns/obscure:
Chambers Brothers - New Generation
Great Speckled Bird (Canadian folk duo Ian and Sylvia's amazing country rock record, and the first album produced by 20/21 year old Todd Rundgren) - s/t
Lou Christie Sacco - Paint America Love. He is the dude that did that "Lightning Strikes" song as Lou Christie.
Dion and the Belmonts did an amazing record in 1967 called Together Again that I read described as "soaked in heroin and warped doo-wop influences, driven by garage-band drums and fuzzed guitars." It rocks.
Along the same lines, early 60s rock/country star Del Shannon (of "Runaway" fame) has a pretty crazy later 60s album called The Further Adventures of Charles Westover that is a good time. And Chubby Checker's later album "Chequered" is a departure from what you might think of when you think Chubby Checker.
These are a few things that popped into the brain.