penny grass vs field pennycress

penny grass and field pennycress both are nouns.

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

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

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

Other synonyms of penny grass include fanweed, French weed, mithridate mustard, stinkweed, Thlaspi arvense.

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