I'm a cross-dressing 'lesbian' wammer! (I say that to avoid confusion as 'straight' would depend on whether I'm in male or female mode. Hopefully that now makes sense so I'm *not* looking for 'male admirers', thanks! (GGs - definitely!) ;-) )
There is nothing that looks, feels and sounds as good for wamming as several layers of tights (pantyhose). I can't resist - No other clothing feels the same or gives the same effects.
By far the best thing to pour into them is soft smooth, creamy, sloppy, clean-washed clay. The feeling and sound of it squelching around in there are unimaginably fantastic. I always crossdress when wamming as a bloke's clothes aren't made from clingy, smooth lycra, which hold all the slop where you want it. It would be such fun to find a wamming g/f and pour the clay into each other's tights!
I also occasionally get to go mountain biking and am always interested to hear of locations not too far from Lancashire/Merseyside/Cheshire (UK) where I can ride through the mud ... and fall off in it, of course! :-)