Your mom had good taste. I grew up with the first Grass Roots album--it was actually more folk and less pop than their later works (including a Bob Dylan cover). The makeup of the band is really complicated--at first, there wasn't a band, just two songwriters. Here's an AllMusic account: https://www.allmusic.com/artist/the-grass-roots-mn0000070773/biography

To go along with the kitchen nostalgia, here's Jimmy Webb singing his composition about one of the Grass Roots founders, P. F. Sloan: https://youtu.be/5_W9HLWZfOo