Samaras

As kids, we called them helicopters.
 
Double- and single-winged seed pods fell from trees by the thousands each autumn, and we would gleefully fling them into the air to watch them spin earthward. My grandson does the same thing now, but I think he prefers calling them whirlybirds.

Silver maple samara (USGS Bee Inventory and Monitoring Lab) Public Domain

Looking closely, you may be surprised to see how much samaras look like insect wings. They probably evolved in a similar manner for the same reasons.
 
Botanically, they are called samaras.
 
Samaras are a type of fruit, called achenes. The seeds we blew from ripe dandelions are also achenes. Achenes are indehiscent, simple dry fruits. [Indehiscent means they do not split open the way pea pods do.]

Vine maple samara (Walter Siegmund) CC BY-SA 3.0

Samaras are notable for their papery wings. You can use the number of wings and the position of the seed to help identify the tree in question. If the seed is found in the middle of a pair of wings, it is likely to be bushwillow, elm, or hoptree.

Bushwillow samaras (Marco Schmidt) CC BY-SA 3.0

Hoptree samaras (Georg Slickers) CC BY-SA 4.0

If the seed is found at one end, it is ash, mahogany, or maple. British sycamores (Acer pseudoplatanus) may have three or four wings.

Those wings help seeds disperse further from the parent tree. Wind dispersal (anemochory) is a primitive form of spreading genetic information, but it works.
 
Most samaras are fun to play with, and I encourage you to do so. The only exception is the African itching plant (Sphedamnocarpus pruriens). Apparently, that one lives up to its nickname.

My grandson and I will stick with the maples.

African itching plant samara (JMK) CC BY-SA 3.0