Why No Nuts on Rosh Hashanah?

There is a custom, mainly among Ashkenazic Jewry, to refrain from eating nuts on Rosh Hashanah. There are different reasons given for this custom, each impacting the parameters of what (and when) exactly we refrain from eating.

Praying Properly
One reason given is that nuts tend to increase saliva and phlegm, making prayer difficult. Since we do a lot more praying on Rosh Hashanah, combined with the importance of taking extra care on this day that our words are enunciated clearly, we avoid eating nuts.1

Keeping Away From Sin
A more mystical reason given is that the numerical equivalent of the Hebrew word for "nut," אגוז (egoz), is 17. Seventeen is also the numerical equivalent of the Hebrew word for “sin,” חט (chet), not as it's properly spelled, but as it’s pronounced. We stay far away from anything reminiscent of sin on Rosh Hashanah, nuts included.2

On Rosh Hashanah, which is the day man was created and ultimately sinned by eating the forbidden fruit, we are extra careful both in eating symbolic foods with auspicious allusions and by avoiding those with negative connotations.3


https://www.chabad.org/library/article_cdo/aid/746604/jewish/Why-No-Nuts-on-Rosh-Hashanah.htm

Shana Tova. One can always hope