Flaxseed rhymes with:
aniseed, appleseed, cottonseed, linseed, oilseed, rapeseed, airspeed, aniseed, appleseed, ashmead, centipede, certainteed, cottonseed, duckweed, fireweed, ganymede, goodspeed, highspeed, inbreed, krumwiede, linseed, lockheed, milkweed, nobody'd, nosebleed, oilseed, pitied, pokeweed, proofread, ragweed, rapeseed, rosemead, seaweed, siegfried, windspeed
Flaxseed sounds like:
falgoust, falgout, falsehood, falsetto, falsity, felicetti, felicitate, felicite, felicity, filched, filegate, flaccid, flagday, flagged, flashed, flashiest, fleeced, fleshed, flexed, flight, flighty, flocked, fluctuate, fluctuated, flushed, full-sized, fullest