Hi Godscreator and welcome to the Nexus!

There is no evidence at all that dmt is produced by the pineal gland, or whether it is produced while we sleep or die. All these are just Strassman's hypotheses(=not facts).

dmt is however produced in the body in trace amounts yet its role is unclear. And yes, it is the same dmt that is found in plants. Just line the amino acids, nucleic acids, lipids are more-or-less the same between different organisms.

Hope that clarifies the situation!