How do you identify an unknown bulb before planting it? ?

I’ve had this happen before with old bulbs that I found in a part of the garden where I hadn't planted anything myself. Before putting them in the ground, I usually try to figure out what they are first, since different bulbs can have very different planting depths and growing requirements. If there are no flowers yet, it can be surprisingly difficult to tell them apart just by looking at the leaves. I’ve used a bulb identifier https://botanapp.com/identifier/bulbs when I wasn't sure what I was looking at, although I’d still compare the result with the plant’s characteristics before planting it.