Kouadri Mohamed El Amine, I am not suggesting only curious if this is even a possibility. The mushroom was surface sterilized the same way as you would sterilize a leaf segment or root segment to culture endophytic fungi. I have never heard of a fungus living inside another fungus. I didn't think anything would grow but as shown in the image, there is growth from the mushroom segments.

Fleshy agaric fruit bodies, and apothecia, are not 'solid' pieces of tissue like, say, a vertebrate animal, or vascular plant, where cells are connected to form tissues and organs, but interwoven hyphae. I think it highly likely, therefore, that some mycelial fungi will be able to 'invade' fungal fruit bodies, with their hyphae growing through the spaces between the individual hyphae. Some individual Coprinus basidiocarps. have been shown to produce cultures of different Coprinus spp. when cultured [RFO Kemp].There are, of course, some parasitic fungi which may not be evident when a sample is collected. Squamanita is a particular case, as it invades and takes over its host - see

https://www.glasgownaturalhistory.org.uk/gn27_1/OReilly_Mitchell_Sqamanita.pdf