Plastic tarp beneath the dirt - is this needed? I was trying to garden, and I be digging holes in...

I was trying to garden, and I be digging holes in the ground and at hand was this sort of plastic tarp underneath the soil-I'm not sure what it was for, but I didn't remove it. I really required to plant flowers there and I merely have a small amount of space surrounded by my front lawn. Does anyone know if to be exact needed. I live in Illinois if that help (the weather)
Answers:    It was possible put down as a weed barrier. The problem beside using plastic is that it is not permeable...so no water flows through.

If you are planting a few shrubs and flowers freshly slice a large "x" shape within the plastic, fold back the plastic, plant your plant, backfill, and consequently fold the plastic back down and mulch around it so you can't see the gross plastic.

If you are planting vegetables then the plastic probably desires to come up. plants can't push through it and cutting dozens and dozens of holes contained by it is not practical and defeat the purpose of having a weed balustrade anyway.
if it is a woven mat that can allow water to flow through after cut a hole and plant your plant.if it is just plastic after rip it all up.plastic on a garden is only unviable.the soil cant exchange air or river.plastic can also encourage fungal growth an if permit long enough can turn your soil infertile.put a garden boundary marker in instead so it disencourages grass from growing contained by your garden