Disclaimer: Do not ingest wild plant extracts in any way without first knowing exactly what is in them.To answer the question, there are a few plants in the midwest purported to be decent sources of DMT. Depending on where you live of course...
In order of most promising to least (imo):
Desmanthus leptolobus is reported in KS, MO, OK, TX
Phalaris brachystachys is reported in AZ, CA, DC, HI, MS, MT, NC, OR, SC, TX, VA
Desmanthus illinoensis is reported in AL, AR, CO, DC, FL, GA, IA, IL, IN, KS, KY, LA, MD, MN, MO, MS, NC, ND, NE, NM, NV, OH, OK, PA, SC, SD, TN, TX, UT, VA, WI
Phalaris aquatica is reported in AZ, CA, DC, HI, MS, MT, NC, OR, SC, TX, VA
and of course Phalaris arundinacea grows almost everywhere: Reported in AK, AL, AR, AZ, CA, CO, CT, DC, DE, IA, ID, IL, IN, KS, KY, MA, MD, ME, MI, MN, MO, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SD, TN, UT, VA, VT, WA, WI, WV, WY