Alas, I was alone at Berlin Pond this morning and you will all think I'm crazy.
BUT, here's the scoop. I was at the end of the pond, about 40 to 50 yards east of the boat ramp, looking on the opposite side of the road from the pond. I heard an unfamiliar chip sound and decided to figure it out. I brazenly pished a bit and up popped am amazingly yellow bird, the color of the dandelions on the side of the road - the whole head, the whole front, with a bill larger than most warblers, and a kind of olive-gray shaded back. NO Yellow Warbler breast streaking. Just plain BRIGHT yellow, top to bottom. It was in the thickets there so i couldn't see the tail part. There were NO wing bars. NOT a blue winged warbler.
I can't think what else it could be - seems to match exactly the guide book descriptions, which I unfortunately went back to my car to consult. I couldn't find the bird when I went back. And of course there is one in Pittsfield, so it's not out of the question!!