The yellow goo could be a new form of DMT aggregation as we fumble to figure out de-polymerization.

Which solvent are you using? Turns out this could be very important.

I think trying to convert it to xtals is easiest to see if it is indeed DMT. Analysis would be best, but not always easily available. I guess heating is another option, DMT oxide reportedly  doesn't vaporize well (see this). DMT oxide is unlikely to be in our extractions I believe.

Plant oils are unlikely I believe. As a check, once I did an acid defat and freeze precipitation and got nothing. I think oils shouldn't care if they are being pulled from an acid or a base.

My guess is that the yellow stuff is DMT that is partially de-polymerized. Could be new for you since we are trying to (in theory) de-polymerize it. Just a guess on my part.