Option 1

The simple way to lead is to invite people to make up a line for the song whether they 'fill in the gap' in this chant:

"I went and found a...."

I suggest they use their time in that place to inspire a line...

For example... 

Option 2

I tell people that I am now going to send them out to forage for some words, or lines, to add to the chant

"I went and found a...."

I invite them to go on a solo wander across the land and to return when (a certain time is reached... they hear they return call (and to stay within audible distance)... when the sun sets etc...).

As they wander they I ask them to remain as present as possible, to expand their senses, to be in the now, but bearing in mind that chant, so that when they return, they can call to mind some highlights from their time on the land and add them as lyrics to the chant, as their turn comes round when we gather and sing the song.