No, there is no hiragana or katakana for either of these, because there was no "ye" or "yi" sound in Japanese at the time that hiragana and katakana were invented, around 800 to 1000 A.D. See How did katakana and hiragana originate?
Because the "ye" sound at least did exist in the Japanese language of the period before the creation of hiragana and katakana, the man'yōgana system (see What is man'yōgana?), which predated hiragana and katakana, did contain representations of ye, "江", and a kana ei (曵) that may also have represented ye. (One kana per "sound" is a relatively modern development.)
The distinction between e and ye was lost by the time of the development of hiragana and katakana. Many people think the ye pronunciation won out (and that is the one used in southern dialects, to a large degree), to change to e during the Edo period.
The kokugakusha of the Edo period (1603-1867) investigated the spelling of the late Nara/early Heian period, and it came to be reinstated as rekishiteki kanadukai (歴史的仮名遣い) (see What is historical kana usage?) and was taught until about 1950 in Japanese schools. Wa, wi, and wo (vs. ha, hi, ho and i, o) were also revived as spelling distinctions, like distinguishing "right" and "rite" in English, or "knew" and "new". However, there was no attempt to revive the e/ye distinction in spelling.
The "y" in the name of the Japanese currency, "yen", and such names as "Yebisu beer", is an artifact of a romanization system. See Where does the word yen come from?
Edited from posts by Bart Mathias and NAKANO Yasuaki. Thanks to Ben Monroe for some more input.
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