Yuppers. What you have there with a baby cucumber attached to the base of the flower is the FEMALE cucumber flower. These are the ones that, when pollinated, will grow into cucumber fruits. The flowers you have been seeing on the cucumber plants, that had NO baby cukes attached were the MALE flowers. Their sole function is to produce pollen and have them transported to the female blossoms to pollinate them. usually they are open for one day only.
Wasps and flies, ants, even hummingbirds can also transfer pollen to the female blossoms. Easiest way to do this yourself is to pluck a male blossom and have it "kiss" -- face-to-face -- a female blossom.
The tomatoes are looking good! Those flowers are self pollinating. The cone shaped yellow part is called "anther cone" and produce pollen inside. Wind or bee buzzing on the blossom causes the pollen to be released and "snows" over the female part of the blossom inside or just protruding from the cone (usually inside). You can simulate the bees by touching the arching stem of the blossoms with an electric toothbrush. It is kind of fun because you will actually see pollen come right out of the anther cone. Same thing can be done with peppers and eggplants.
But I see in your windowbox, spinach, basil, and what looks like corn seedlings?
Cucumber is a member of cucurbit family -- cucumber, squash, melon, gourd -- and normally they each have both male and female blossoms. IME typically the male blossoms start opening about a week to 10 days before female blossoms show up and open, but I have heard others have seen opposite sequence.
There are newer hybrids that grow mostly female blossoms with separate male pollinator hybrid -- I can't remember what they are called, but these are sold with a 2nd small packet of male variety seeds inside the packet of larger number of female variety seeds.... Or sometimes the two varieties are mixed in a packet and you need to plant the entire packet to be sure of planting the males. I never get this kind because I wouldn't have the room to grow that many.
There are also parthenocarpic hybrid varieties which do not need to be pollinated to develop fruits which are meant for greenhouse and hoop house culture with no insect pollinators. I have heard that these if pollinated, develop fruits that are not as good eating in some way.
So I managed to get a pic of one of the 50ish mini flys that cawl on the dirt in my main hub. They have wings but ive never seen them fly. Any guesses?
I also show a pic of something thats been going around from flower to flower "pollinating"I hope. Looks like baby wasp without the stinger.
Attachments
This thing...
Mini fly? Hard to get them when they aren't moving.