At first, I was thinking insect egg mass, as with Lymantria. I know, gypsy moth masses are more buff-colored, but very new masses? I don't know much about insects.
When I read more closely about the mass being palm sized, I'm thinking slime mold. Very young Fuligo can be off-white before they mature.
Is it still that color? does it still "give" when pushed? What does it look like on the inside? Also where are you located? That can help with ID.
I haven't dared cut into it but now I'm thinking I should tomorrow? I'm in Montreal, QC, Canada. It's been rainy all week and cool. What really caught my eye was the color and odd sheen. It's got a pearl-like color. And it's completely smooth. I was expecting it to be rock hard but then it nudges.
I came across something like this and choked it up to a immature puffball. It was frowning inside a crack about 4’ off the flare on a bigleaf maple. Oddly right above some old ganoderma FBs, slightly above that last years old dried up puff ball. It was literally about the texture of a marshmallow. I only took a video, so can’t post it here.
Yep - False Puffball. Also known as moon excrement in Mexican folklore . Usually grows on dead wood which is a bummer for my magnificent willow. The branch it's growing on is not doing well at all but it's been cabled a few years back so my arborist assures me it's not going anywhere soon.
I saw something similar but much smaller (maybe an inch in diameter) on a silver maple yesterday. It was a little more gray, but still "pearly". It did "puff" when I pushed on it, so yeah...I'd have guessed those was similar to a puffball. See if you can get back to it in a couple of days.
I've never heard that common name, but I'm heartened that I was on the right track with thinking it a slime mold. Reticularia and Enteridium both refer to a single well-recognized genus. Experts are divided on which genus name should be used. It's an "inside baseball" sort of call on naming priority. I go with the earlier Reticularia lycoperdon. The sharp eyed will note the species epithet (the second word in the double-barrel scientific name). Lycoperdon (meaning wolf skin) is the genus name for the most common puffballs. So the name of the false is linked to the name of the true.