field pennycress vs penny grass

field pennycress and penny grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
field pennycress	Yes	No	No	No
penny grass	Yes	No	No	No

As nouns, field pennycress and penny grass are synonyms defined as:

field pennycress and penny grass: foetid Eurasian weed having round flat pods; naturalized throughout North America

Other synonyms of field pennycress include fanweed, French weed, mithridate mustard, stinkweed, Thlaspi arvense.

field pennycress (noun)	penny grass (noun)
foetid Eurasian weed having round flat pods; naturalized throughout North America	foetid Eurasian weed having round flat pods; naturalized throughout North America