I waited way too long to mow my backyard, and as a result, I have alot
of clippings... can these be used to mulch around my tomatos and
peppers, cuces, etc?? or am I asking for disaster? I guess the
clippings would provide good organic matter when they get tilled
under, but will they let enough water past into the soil?? will there
be any other problems I need to look out for??

thanks for the input!!

Yes grass clipping make excellent mulch for vegetables. As long as you only put
them a couple of inches deep, you should have no problems with water
penetration. I use leaves rather than grass clippings on tomatoes, in something
of an attempt to hold down foliar diseases, but the clippings are better than
bare soil.