Russian Olive (Elaeagnus angustiofolia), fam. Elaeagnaceae.
The flowers appear by the end of May, having very fragrant, not similar to anything other aroma (it is even rather annoying in large quantities). The fruits are floury, astringent, and sweet. The Kyiv summer is not long and hot enough for the fruits to ripen completely, which happens with them in southern Ukraine in September. Russian Olive is also a source of astringent remedies to treat digestive tract diseases.
It bears severe droughts and soil salinity, that is why in prairie lands these "wild olives", growing both alone or in groups, are the only source of shadow in hot days over the space of many kilometers around.