Nope, unless something radical has changed in the last 3 years since I left you talked to a bureaucrat that gave you bad info.
The Johnson County Parks charge $6 for a permit good for a year, from Jan 1 till Dec 31 so I always got mine early in Jan to get full use out if it.
I bought them at my favorite park, Shawne Mission, but any parks in the system that have an office sells them.
Might be a few bucks more if you don't live in Johnson County but so what...I used to find hundreds in clad at their parks per year and silver and gold worth a few thousand.
Olathe issues free yearly permits and you can get them online through their website.
If you hunt in any of these parks it is best to have and carry them with you because Rangers do stop and ask you to see them, once they get to know you they just wave after that.
KCMO parks, there are no rules in their parks so you can dig there so i dont know what that person was talking about.
Stop calling and asking them because it just winds them all up and who knows what will happen.
Cities have banned metal detecting in the past after decades because somebody called the wrong person in the city offices and they decided they did not want anybody digging in their parks, anywhere.
All info about MD rules are online for most cities and counties.
You don't need permits and neither do most other areas or cities I hunted except one...Prarie Village over the border in Kansas.
They have that stupid you can scan all you want but can't dig, rule, so I visited that city once and never went back.
If there are rules, they are minimal.
I believe Wyandotte County outlawed hunting but the greatest metal detecting club with the greatest group of people in the country worked to get that overturned....
http://www.mwas.org/forum/index.php
Now you can hunt but holes should be not much wider than or deeper than 6".
Join their club or at the least join their forum and ask those guys because they know the rules.
You got great dirt in your neck of the world, easy to get permits if you need them and no permits in most other places so if you make sure you dig good plugs and clean up after yourself you should have no problems.
As far as targets, those parks are loaded with them and trust me, I culled a large amount of them but I left you some.
I hunted all over Swope...a lot.
Our club frequently had monthly meetings there up in the boys out camp area which is off limits to hunting but we had permission and we found silver up there.
Found a ton of great stuff in that huge park in many different areas including climbing up a mountain into the woods where bike trails now rule.
Did you know that those bike trails originated as horse trails and back in the day, late 1800's to early 1900's and people hung out all over that mountain riding, camping, losing horseshoes, horseshoe nails and other tack galore, plus enough tin and aluminum foil to cover a Thanksgiving float.
You might not know that foil really never goes away...ever.
This was where people used to hang out and have fun, pre TV days.
I was looking for Barber dimes, a bucket list coin I knew others had found at Swope in the past, but I never did find one there.
I did find a few other silver coins in those woods and a bunch of other great things, though.
http://metaldetectingforum.com/showthread.php?t=176267