Josh, looking for a single sine oscillator phase-mod feeding back on itself, or a "Sytrus-style" general PM feedback matrix?

I've done both, and could dig up examples.

(p.s. I like to use the term PM as opposed to FM, because it's really more accurate. At least in the digital realm, what we're doing is

taking output of an oscillator and modifying the phase location of another, or, in other words, adding a wave output to a phasor

and doing lookup into a table from that (or, directly calling `sin` from it))