Mr. Tambourine Man
Bluelighter
For me, visually, everything seems 3x sharper... my eyes are good to begin with but grass really makes things seem crisper. My hearing is also very enhanced, and I can hear quieter or farther away sounds with much greater clarity than when sober. My thought process become highly tangential, and elaborate, which would be wonderful if it weren't for the typical "6 seconds and its gone forever" effect weed has on one short term memory. Textures, particularly outdoors, are very pronounced, especially if one is stoned enough to get light visual distortions. Sitting in a garden or museum while baked is the best! 
Also, grass reduces some of my inhibitions while at the same time making me more self-conscious (not necessarily in bad way). I can communicate fine with people I already know when baked, but unless they are understanding of my state, my mind won't really be on the conversation. For some reason, when I'm high, I can't simply go indoors and vegetate, I feel the urge to walk or bike. For some reason sitting around inside doing nothing when I'm stoned feels very depressing.

Also, grass reduces some of my inhibitions while at the same time making me more self-conscious (not necessarily in bad way). I can communicate fine with people I already know when baked, but unless they are understanding of my state, my mind won't really be on the conversation. For some reason, when I'm high, I can't simply go indoors and vegetate, I feel the urge to walk or bike. For some reason sitting around inside doing nothing when I'm stoned feels very depressing.