Corydalis
There seem to be two native Corydalis varieties to PA
C. flavula - the more common kind (called pale corydalis commonly on iNaturalist)
It's flowers are about half the size of aurea, and it has a prominent crest. Also is said to prefer wetter habitats.
This article is regarding it's presence in Connecticut
https://www.nativeplanttrust.org/documents/46/Corydalisflavula.pdf
http://www.kansasnativeplants.com/guide/plant_detail.php?plnt_id=794
C. Aurea - the rarer kind, threatened in PA and of unknown status through most of the US
(called yellow corydalis as its common name on iNaturalist)
http://ontariowildflowers.com/main/species.php?id=820
A Chicago Journal (https://www.journals.uchicago.edu/doi/pdf/10.1086/325978)
described them thusly:
C. AUREA Willd. Commonlv spreading and with slender pedicels: spur of
corolla barely half the length of the body, somewhat decurved: capsules pendulous or spreading, terete, toruiose when dry: seeds turgid, obtuse at margin,
the shining surface obscurely reticulated under a lens.
C. FLAVULA DC. Flowers conspicuously bracted and slender-pedicelled:
outer petals surpassing the inner; crest very salient, 3 to 4-toothed: capsules
pendulous seeds acutely margined, rugose-reticulated, at least toward the
margins.-C. flavidula Chapman, Fl. ed. 2, 604, a slip of the pen.
Non-Native Corydalis
Three common non-native Corydalis in our area: C. Incisa (invasive), C. solida and C. cava.
All usually have purple flowers or some hue close to that. (solida seems to come in a variety of colors including pink and white).
Corydalis incisa (Incised fumewort) - seems to be a prevalent non-native in PA. If in flower it seems fairly obvious. It has more jagged, toothed leaves than any of the other corydalis, but I am not sure if they can be confounded with anything else (they remind me a lot of parsley, so if confronted with only leaves I'm not sure I would dare identify yet). There seem to be a number of articles about this invasive - it seems to be a big problem in NY
https://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/wra/corydalis-incisa.pdf
https://libguides.nybg.org/invasiveplants/corydalis_incisa_display
http://phytoneuron.net/2014Phytoneuron/96PhytoN-Corydalisincisa.pdf
https://libguides.nybg.org/invasiveplants/corydalis_incisa_display
Corydalis solida (Bird-in-a-Bush) is also a possibility, although less widespread. No good websites pop up readily for this species, but it has wider, lobed leaves than incisa. These look like they could be confused with Rock Harlequin or other fumaria species if not in bloom.
http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200009131
https://www.discoverlife.org/mp/20q?search=Corydalis+solida
C. cava - encountered infrequently, but it can be confused with solida. It will have sepals with no divisions in them ( a sort of pointed, teardrop shape), while solida has divided sepals (like a handprint, kind of).
(5/6/22 edit) I just heard about a hybrid between solida and cava called Corydalis x campylochia. Good discussion on this observation:
https://www.inaturalist.org/observations/113824229
There is not much information about identification of this hybrid, but it can be seen on this page about corydalis rot. Apparently the bracts show a few weak teeth sometimes in it.
http://www.blumeninschwaben.de/Zweikeimblaettrige/Erdrauchgewaechse/corydalis_rot.htm#7
Corydalis cava, solida and x campylochia are all shown side by side here on the same site.
http://www.blumeninschwaben.de/Zweikeimblaettrige/Erdrauchgewaechse/corydalis_rot.htm
Other reference sites about non-native corydalis:
https://www.pacificbulbsociety.org/pbswiki/index.php/CorydalisSpecies
https://frustratedgardener.com/2017/03/21/crazy-for-corydalis/