Beginning of new Hebrew month of Iyyar. Iyyar (somtimes transliterated Iyar) is the 2nd month of the Hebrew year. Corresponds to April or May on the Gregorian calendar

https://www.hebcal.com/holidays/rosh-chodesh-iyyar-2021?utm_source=js&utm_medium=icalendar

Israeli Memorial Day. Note that Hebcal displays modern holidays like Yom HaZikaron according to the Israeli schedule. Although Yom Hazikaron is normally observed on the 4th of Iyyar, it may be moved earlier or postponed if observance of the holiday (or Yom HaAtzma'ut, which always follows it) would conflict with Shabbat

https://www.hebcal.com/holidays/yom-hazikaron-2021?utm_source=js&utm_medium=icalendar