For suits of playing cards: Spades, Diamonds, Hearts, Clubs
Four of us are in your field
But our differences keep us at yield
First, a one that is no fool
Though he resembles a gardener's tool
Spade-
A sturdy digging tool having a thick handle and a heavy, flat blade that can be pressed into the ground with the foot.
Next, one difficult to split in two
And a girl once had one as big as her shoe
Diamond- An extremely hard, highly refractive crystalline form of carbon that is
usually colorless and is used as a gemstone and in abrasives, cutting
tools, and other applications.
Then, to the mind, one's a lovely bonder
And truancy makes it grow fonder
Hearts
Last, a stem connecting dots of three
Knowing all this, what are we?
Clubs- A black figure shaped like a trefoil or clover leaf on certain playing cards.