Tautonym is when the genus and species are the same, write below an example! And try not to use google! 
I start!
Curaeus curaeus! Austral blackbird, which is also, triple tautonym :P
Bufo bufo, a toad
Bison bison, a bison 
Tautonyms are surprisingly common, a couple examples include:
Honorable mention: Gekko gecko, which is only one letter off from being a tautonym.
Bison bison bison is even better
Damn. I thought so but I didnāt want to use Google and break the rules.
Ariadne ariadne, a butterfly
Vulpes vulpes red fox
Fun fact, tautonyms are actually forbidden in plant names, but that doesnāt stop people from trying:
Arctostaphylos uva-ursi, which translates from first Greek and then Latin as something like bear grapes bearās grape
Araucaria araucana is pretty confusing
and then we have these suffixes -opsis and -oides which both mean ālikeā as in āsimilar to.ā I canāt think of it off the top of my head but I am pretty sure there was some plant that was cheating by just taking the genus name and adding the suffix to make the species epithet.
Gulo gulo : wolverine
Gorilla gorilla gorilla. As Sam OāNella so eloquently put it, āitās the gorillest gorilla that ever gorilledā
Unrelated, but i thought of this https://en.wikipedia.org/wiki/Buffalo_buffalo_Buffalo_buffalo_buffalo_buffalo_Buffalo_buffalo
If I remember correctly there is a Rattus rattus.
You may have been thinking about Thalictrum thalictroides perhaps? And Iām sure there are others like that.
Grus grus
Pyrrhula pyrrhula ssp. pyrrhula
Spinus spinus
Regulus regulus ssp. regulus
Curruca curruca ssp. curruca
Ciconia ciconia ssp. ciconia
Gallinago gallinago ssp. gallinago
Tadorna tadorna
Oenanthe oenanthe ssp. oenanthe
Buteo buteo ssp. buteo
Vanellus vanellus
Apus apus ssp. apus
Ok, Iām done, take any bird and thereāll be it.
Gorilla gorilla gorilla (oh, itās been mentioned already)
Boops boops, even knowing the etymology it will never stop being funny to me.
I complained about this one, but, Linnaeus had it in a different genus before, so it was ālike an ericaā Must keep the old, first, name however wrong and UNhelpful it is.
https://www.inaturalist.org/taxa/584815-Erica-ericoides
Golden, first in Greek, then in Latin
https://www.inaturalist.org/taxa/129068-Chrysocoma-coma-aurea
Grus grus is a fine example. When I was young, I was convinced the word āGrusā meant both ācommonā and ācraneā before I learned scientific names didnāt always apply to common names.
Shakira shakira?