That's a tricky one. A little more info may help us:
Is it just your plot, or others nearby too?
Are you at the bottom of a slope?
What's your soil made up of? Mainly clay?
Is there a stream, river, road culvert or drain nearby which is overflowing?
Flooding can be caused by several things, such as a high water table or a 'pan' under the surface - a compacted layer of soil or clay, sometimes caused by mechanical cultivation, through which the water cannot drain.
Raised beds often help, although if it's a pan then digging to break it up would help.